New Testament Canonization

New Testament authors quoting other parts of the New Testament as authoritative Scripture
Paul recognized Luke's Gospel as scripture
For the Scripture says, "You shall not muzzle an ox when it treads out the grain," and, "The laborer deserves his wages." (1 Timothy 5:18 ESV)
When Paul wrote to Timothy he quoted a passage from Luke 10:7 as Scripture. This also proved that the Gospel of Luke and the Acts of Apostles were finished and in circulation before Paul wrote the first epistle to Timothy. This collaborate with Acts 28:30-31 which was written by Luke, and finished off with Paul's first imprisonment. It also established the date of the epistle's writing as between Paul's first and final Roman imprisonments.

Peter recognized the letters of Paul in circulation as scripture
And count the patience of our Lord as salvation, just as our beloved brother Paul also wrote to you according to the wisdom given him, as he does in all his letters when he speaks in them of these matters. There are some things in them that are hard to understand, which the ignorant and unstable twist to their own destruction, as they do the other Scriptures. (2 Peter 3:15-16 ESV)
Peter recognized the scriptural authority of Paul's letters and warned against twisting the words of Paul to justify heresies.

New Testament authors knew they were writing authoritative Scripture
Paul knew that he is writing scripture
If anyone thinks that he is a prophet, or spiritual, he should acknowledge that the things I am writing to you are a command of the Lord. If anyone does not recognize this, he is not recognized. (1 Corinthians 14:37-38 ESV)
Now to him who is able to strengthen you according to my gospel and the preaching of Jesus Christ, according to the revelation of the mystery that was kept secret for long ages but has now been disclosed and through the prophetic writings has been made known to all nations, according to the command of the eternal God, to bring about the obedience of faith - to the only wise God be glory forevermore through Jesus Christ! Amen. (Romans 16:25-27 ESV)
And we also thank God constantly for this, that when you received the word of God, which you heard from us, you accepted it not as the word of men but as what it really is, the word of God, which is at work in you believers. (1 Thessalonians 2:13 ESV)
So then, brothers, stand firm and hold to the traditions that you were taught by us, either by our spoken word or by our letter. (2 Thessalonians 2:15 ESV)
He declared that a true prophet would recognize that his letters are the command of the Lord.

Peter knew that he was writing scripture
I want you to recall both the predictions foretold by the holy prophets and the commandment of the Lord and Savior through your apostles. (2 Peter 3:2 NET)
Peter put the writings of the apostles (including himself) on par with the prophecies of the Old Testament.

John knew that he was writing scripture
The revelation of Jesus Christ, which God gave him to show to his servants the things that must soon take place. He made it known by sending his angel to his servant John, who bore witness to the word of God and to the testimony of Jesus Christ, even to all that he saw. Blessed is the one who reads aloud the words of this prophecy, and blessed are those who hear, and who keep what is written in it, for the time is near. (Revelation 1:1-3 ESV)
John explicitly stated that the book he was writing was a revelation from Jesus Christ Himself. With the completion of Book of the Revelation of Jesus Christ in about AD 95-96, the New Testament is closed. All books written after Revelation and claimed to be revelations of the God of Abraham from angels or prophets or the apostles or successors of the apostles are all false.

The following quote from this article "Early Christians Believed that Canonical Books were Self-Authenticating" by Michael J Kruger summarized an important point on the canonization of the New Testament - it is canonized by God, not men.

QUOTE
In the end, the church fathers teach us a very important truth.  The NT canon we possess today is not due to the machinations of later church leaders, or to the political influence of Constantine, but due to the fact that these books imposed themselves on the church through their internal qualities.
UNQUOTE

Canonisation of the New Testament

Criteria

1. The message
Christ died for our sins and He was buried and raised the third day (1 Corinthians 15:3-8)

2. The authors of the message
The apostles and their associates were eye witnesses of the death, burial and resurrection of Christ (John 21:24-25, 1 Corinthians 15:3-8, 1 Peter 5:1, 2 Peter 1:16-17, 1 John 1:1-3).
While Luke is not an eyewitness of the acts and miracles of Jesus, he was a eyewitness to the acts and miracles of Paul the apostle. (Luke 1:1-4, Acts 2:32, Acts 3:15, Acts 4:20, Acts 4:33, Acts 10:39-42)
Criteria of an apostle - eyewitness and with us from the beginning (Acts 1:21-22)

Condition

1. Christians were persecuted
Being a Christian in those days meant persecution that may result in death.

Process

1. By consensus, not officially sanctioned in an official meeting
As in many things in Christianity, such as the spread of Christianity in the first 200 hundred years (done not with political blessing nor power of the military, but by unknown itinerary preachers).
the acceptance of the New Testament was by consensus, not dictated by an official authority.

2. Eyewitnesses
Eyewitness authority of Paul (2 Peter 3:15-16), the apostles and their associates were recognized from the beginning. Matthew, Mark, Luke, John, Acts, and the letters of Paul were accepted, but there were some uncertainties about the general epistles.
In AD 367 the first historical list of all 27 New Testament books were listed in 39th Festal Letter by Athanasius bishop of Alexandria. The quote below were taken from this article in Christianity Today:
QUOTE
Athanasius wrote the list to end disputes about such texts as "The Shepherd of Hermas" or "The Epistle of Barnabas" which long had been regarded as equal to the apostolic letters. He also silenced those who had questioned the apostolic authenticity of Peter’s letters or the Book of Revelation. Athanasius states that "in these [27 writings] alone the teaching of godliness is proclaimed. No one may add to them, and nothing may be taken away from them."
UNQUOTE

Reference:
Do We Have the Right Books in the Bible? | Grace Communion International
367 Athanasius Defines the New Testament | Christian History
The Case for the Eyewitness Status of the Gospel Authors | Cold Case Christianity
The Apostles Wrote the Gospels as Eyewitness Accounts | Cold Case Christianity
How Can the Gospels Be Eyewitness Accounts If They Include Things the Writers Didn't See? | Cold Case Christianity

The Canonisation Process

The Bible is our final authority. But how can we be sure that all the books that are supposed to form the Bible is in the Bible? Who decides what goes into the Bible?

Divine perspective:
The short answer is God.
God, acting through human agencies, wrote the books that made up the Bible.
All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work. (2 Timothy 3:16-17 ESV)
First of all, you should know this: No prophecy of Scripture comes from one's own interpretation, because no prophecy ever came by the will of man; instead, men spoke from God as they were moved by the Holy Spirit. (2 Peter 1:20-21 HCSB)

Human perspective:
The short answer is no one.
Canonization is a process. While the Bible is canonized, the history of the process of canonization is not canonized. There is no authorized record of how the books got into the Bible, just various historical records on how the Old and New Testaments were canonized.

The Word of God Sustains All Things

And God saw everything that he had made, and behold, it was very good. And there was evening and there was morning, the sixth day. Thus the heavens and the earth were finished, and all the host of them. And on the seventh day God finished his work that he had done, and he rested on the seventh day from all his work that he had done. So God blessed the seventh day and made it holy, because on it God rested from all his work that he had done in creation. (Genesis 1:31-2:3 ESV)

But Jesus answered them, "My Father is working until now, and I am working." (John 5:17 ESV)

And he is before all things, and in him all things hold together. (Colossians 1:17 ESV)

The Son is the radiance of God's glory and the exact expression of His nature, sustaining all things by His powerful word. (Hebrews 1:3a HCSB)

But by the same word the heavens and earth that now exist are stored up for fire, being kept until the day of judgment and destruction of the ungodly. (2 Peter 3:7 ESV)

The whole creation seems to work like a clock. Everything works without the need of intervention. So wonderfully automated is this world the many ruled out the need for God. But the Bible tells us that all things are held together by the Word of God.

We can have a analogy (though I would consider it a poor analogy) of a computer system. Once the development of the computer system by the word of men is done and implemented, it still needs the IT Operations to run and maintain it and to hold it together.

We have no idea how the Word of God sustains all things. One day, it may be revealed to us. But until then, we just have to know that although no intervention seems to be needed in nature, God is actually sustaining the whole world by the power of His Word.

The secret things belong to the LORD our God, but the things that are revealed belong to us and to our children forever, that we may do all the words of this law. (Deuteronomy 29:29 ESV)

The Winepress

The scariest event in the calendar of Jesus's second coming - the winepress of the wrath of God.

The place
I will gather all the nations and bring them down to the Valley of Jehoshaphat. And I will enter into judgment with them there, on behalf of my people and my heritage Israel, because they have scattered them among the nations and have divided up my land, and have cast lots for my people, and have traded a boy for a prostitute, and have sold a girl for wine and have drunk it. (Joel 3:2-3 ESV)
Let the nations stir themselves up and come up to the Valley of Jehoshaphat; for there I will sit to judge all the surrounding nations. (Joel 3:12 ESV)
"When the Son of Man comes in his glory, and all the angels with him, then he will sit on his glorious throne. Before him will be gathered all the nations, and he will separate people one from another as a shepherd separates the sheep from the goats. And he will place the sheep on his right, but the goats on the left. (Matthew 25:31-33 ESV)
I tell you, in that night there will be two in one bed. One will be taken and the other left. There will be two women grinding together. One will be taken and the other left." And they said to him, "Where, Lord?" He said to them, "Where the corpse is, there the vultures will gather." (Luke 17:34-37 ESV)

The harvest
Put in the sickle, for the harvest is ripe. Go in, tread, for the winepress is full. The vats overflow, for their evil is great. (Joel 3:13 ESV)
Then I looked, and behold, a white cloud, and seated on the cloud one like a son of man, with a golden crown on his head, and a sharp sickle in his hand. And another angel came out of the temple, calling with a loud voice to him who sat on the cloud, "Put in your sickle, and reap, for the hour to reap has come, for the harvest of the earth is fully ripe." So he who sat on the cloud swung his sickle across the earth, and the earth was reaped.
Then another angel came out of the temple in heaven, and he too had a sharp sickle. And another angel came out from the altar, the angel who has authority over the fire, and he called with a loud voice to the one who had the sharp sickle, "Put in your sickle and gather the clusters from the vine of the earth, for its grapes are ripe." So the angel swung his sickle across the earth and gathered the grape harvest of the earth and threw it into the great winepress of the wrath of God. (Revelation 14:14-19 ESV)

The winepress
From his mouth comes a sharp sword with which to strike down the nations, and he will rule them with a rod of iron. He will tread the winepress of the fury of the wrath of God the Almighty. (Revelation 19:15 ESV)
I trampled the winepress alone, and no one from the nations was with Me. I trampled them in My anger and ground them underfoot in My fury; their blood spattered My garments, and all My clothes were stained. (Isaiah 63:3 HCSB)
And the winepress was trodden outside the city, and blood flowed from the winepress, as high as a horse’s bridle, for 1,600 stadia. (Revelation 14:20 ESV)

See Judgement.

The Coming Mass Extinction

Unbelievers maintained that the earth was always the same.
Know this first of all, that in the last days mockers will come with their mocking, following after their own lusts, and saying, "Where is the promise of His coming? For ever since the fathers fell asleep, all continues just as it was from the beginning of creation." (2 Peter 3:3-4 NASB)

Because of that, they failed to notice that the earth was once destroyed by water.
For they deliberately overlook this fact, that the heavens existed long ago, and the earth was formed out of water and through water by the word of God, and that by means of these the world that then existed was deluged with water and perished. (2 Peter 3:5-6 ESV)

The earth is now preserved for the coming destruction by fire.
But by the same word the heavens and earth that now exist are stored up for fire, being kept until the day of judgment and destruction of the ungodly. (2 Peter 3:7 ESV)

One fourth of the earth's population killed.
When He opened the fourth seal, I heard the voice of the fourth living creature say, "Come!" And I looked, and there was a pale green horse. The horseman on it was named Death, and Hades was following after him. Authority was given to them over a fourth of the earth, to kill by the sword, by famine, by plague, and by the wild animals of the earth. (Revelation 6:7-8 HCSB)

One third of the earth burnt.
The first angel blew his trumpet, and hail and fire, mixed with blood, were hurled to the earth. So a third of the earth was burned up, a third of the trees were burned up, and all the green grass was burned up. (Revelation 8:7 HCSB)

One third of the living creatures in the sea died.
The second angel blew his trumpet, and something like a great mountain ablaze with fire was hurled into the sea. So a third of the sea became blood, a third of the living creatures in the sea died, and a third of the ships were destroyed. (Revelation 8:8-9 HCSB)

One third of the fresh water became bitter.
The third angel blew his trumpet, and a great star, blazing like a torch, fell from heaven. It fell on a third of the rivers and springs of water. The name of the star is Wormwood, and a third of the waters became wormwood. So, many of the people died from the waters, because they had been made bitter. (Revelation 8:10-11 HCSB)

One third of the remaining population killed.
So the four angels who were prepared for the hour, day, month, and year were released to kill a third of the human race. (Revelation 9:14 HCSB)

All the sea creatures died.
The second angel poured out his bowl into the sea, and it became blood like that of a dead man; and every living thing in the sea died. (Revelation 16:3 NASB)

All the unbelievers died.
From his mouth comes a sharp sword with which to strike down the nations, and he will rule them with a rod of iron. He will tread the winepress of the fury of the wrath of God the Almighty. (Revelation 19:15 ESV)
I trampled the winepress alone, and no one from the nations was with Me. I trampled them in My anger and ground them underfoot in My fury; their blood spattered My garments, and all My clothes were stained. (Isaiah 63:3 HCSB)
And the winepress was trodden outside the city, and blood flowed from the winepress, as high as a horse’s bridle, for 1,600 stadia. (Revelation 14:20 ESV)

Once Saved Always Saved - 1

Once saved always saved is a very complex doctrine and tied up with other aspects of Christianity:

1. Grace vs Works.
2. Predestination vs Free Will

I shall go through it slowly and see if I can make myself clear. I shall start with two parables in the Gospel of Matthew.

The Parable of the Sower
That same day Jesus went out of the house and sat beside the sea. And great crowds gathered about him, so that he got into a boat and sat down. And the whole crowd stood on the beach. And he told them many things in parables, saying: "A sower went out to sow. And as he sowed, some seeds fell along the path, and the birds came and devoured them. Other seeds fell on rocky ground, where they did not have much soil, and immediately they sprang up, since they had no depth of soil, but when the sun rose they were scorched. And since they had no root, they withered away. Other seeds fell among thorns, and the thorns grew up and choked them. Other seeds fell on good soil and produced grain, some a hundredfold, some sixty, some thirty. (Matthew 13:1-8 ESV)

The Parable of the Sower Explained
"Hear then the parable of the sower: When anyone hears the word of the kingdom and does not understand it, the evil one comes and snatches away what has been sown in his heart. This is what was sown along the path. As for what was sown on rocky ground, this is the one who hears the word and immediately receives it with joy, yet he has no root in himself, but endures for a while, and when tribulation or persecution arises on account of the word, immediately he falls away. As for what was sown among thorns, this is the one who hears the word, but the cares of the world and the deceitfulness of riches choke the word, and it proves unfruitful. As for what was sown on good soil, this is the one who hears the word and understands it. He indeed bears fruit and yields, in one case a hundredfold, in another sixty, and in another thirty." (Matthew 13:18-23 ESV)

The Parable of the Weeds
He put another parable before them, saying, "The kingdom of heaven may be compared to a man who sowed good seed in his field, but while his men were sleeping, his enemy came and sowed weeds among the wheat and went away. So when the plants came up and bore grain, then the weeds appeared also. And the servants of the master of the house came and said to him, 'Master, did you not sow good seed in your field? How then does it have weeds?' He said to them, 'An enemy has done this.' So the servants said to him, 'Then do you want us to go and gather them?' But he said, 'No, lest in gathering the weeds you root up the wheat along with them. Let both grow together until the harvest, and at harvest time I will tell the reapers, "Gather the weeds first and bind them in bundles to be burned, but gather the wheat into my barn."'" (Matthew 13:24-30 ESV)

The Parable of the Weeds Explained
Then he left the crowds and went into the house. And his disciples came to him, saying, "Explain to us the parable of the weeds of the field." He answered, "The one who sows the good seed is the Son of Man. The field is the world, and the good seed is the sons of the kingdom. The weeds are the sons of the evil one, and the enemy who sowed them is the devil. The harvest is the end of the age, and the reapers are angels. Just as the weeds are gathered and burned with fire, so will it be at the end of the age. The Son of Man will send his angels, and they will gather out of his kingdom all causes of sin and all law-breakers, and throw them into the fiery furnace. In that place there will be weeping and gnashing of teeth. Then the righteous will shine like the sun in the kingdom of their Father. He who has ears, let him hear. (Matthew 13:36-43 ESV)

In the parable of the sower, the seeds fell on four types of ground: the road, rocky ground, thorny ground and good soil. Except for those seeds which fell on the road, the seeds that fell on the other three types of soil initially produced something. Only in the good soil that they persist till the end.

In the parable of the weeds, both wheat and weeds looked the same in the field. It is only at harvest time that the wheat can be distinguished from the weeds.

What has this got to do with "Once saved always saved"?

From the perspective of the world (and some Christians), true and false Christians look alike. Nobody can see their hearts and tell the difference. They grow and produce some fruits. But ultimately, only those who persist till the end are revealed to be true. For those who do not persist, they seem to be Christians who have "fallen away".

The clearest example is Judas Iscariot. Is he not among the twelve? Did he not perform all the miracles that the other apostles did? When Jesus told the twelve that one of them would betray Him, none of them suspected Judas Iscariot.

When it was evening, he reclined at table with the twelve. And as they were eating, he said, "Truly, I say to you, one of you will betray me." And they were very sorrowful and began to say to him one after another, "Is it I, Lord?" (Matthew 26:20-22 ESV)

But the Bible tells us very clearly that Jesus had kept all that was given to Him by the Father.

While I was with them, I kept them in your name, which you have given me. I have guarded them, and not one of them has been lost except the son of destruction, that the Scripture might be fulfilled. (John 17:12 ESV)

I give them eternal life, and they will never perish, and no one will snatch them out of my hand. My Father, who has given them to me, is greater than all, and no one is able to snatch them out of the Father's hand. (John 10:28-29 ESV)

There are many Christians who thought that they are Christians, but are never truly saved. Like Judas Iscariot, they have joined Jesus with other motives. When they fall away, the world thought that salvation can be lost. But the Bible tells us that they are not of us from the beginning.

They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us. (1 John 2:19 ESV)

Again, Judas Iscariot was the best example. Long even before the birth of Jesus, it has been prophesied in the Psalms that one who ate bread together with Jesus would betray Him.

Even my close friend in whom I trusted, who ate my bread, has lifted his heel against me. (Psalm 41:9 ESV)

But no one would have known until it happened. So did Judas Iscariot "fall away" or he was never among the chosen? But Jesus chose the twelve apostles, right?

Jesus answered them, "Did I not choose you, the twelve? And yet one of you is a devil." (John 6:70 ESV)

But Jesus knew whom He had chosen and Judas Iscariot was not among them.

I am not speaking of all of you; I know whom I have chosen. But the Scripture will be fulfilled, 'He who ate my bread has lifted his heel against me.' (John 13:18 ESV)

Once you can understand how Judas Iscariot was chosen and also not chosen, you will know how to interpret the Bible correctly and you will understand why a true Christian is "once saved always saved".

"Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. On that day many will say to me, 'Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?' And then will I declare to them, 'I never knew you; depart from me, you workers of lawlessness.' (Matthew 7:21-23 ESV)