The Consistent Message of Salvation

The consistent core message of the Bible:
Salvation is provided by God and must be accepted by faith
And without faith it is impossible to please him, for whoever would draw near to God must believe that he exists and that he rewards those who seek him. (Hebrews 11:6 ESV)

Death is necessary for forgiveness of sin
Indeed, under the law almost everything is purified with blood, and without the shedding of blood there is no forgiveness of sins. (Hebrews 9:22 ESV)

The consistent message of the Bible is that salvation is provided by God and men have to accepted it by faith. The knowledge of God and the actual mechanics of how the salvation is provided is revealed progressively.

Progressive Revelation:
Shadow to Substance
They serve a copy and shadow of the heavenly things. For when Moses was about to erect the tent, he was instructed by God, saying, "See that you make everything according to the pattern that was shown you on the mountain." (Hebrews 8:5 ESV)

Since the law has only a shadow of the good things to come, and not the actual form of those realities, it can never perfect the worshipers by the same sacrifices they continually offer year after year. (Hebrews 10:1 HCSB)

These are a shadow of the things to come, but the substance belongs to Christ. (Colossians 2:17 ESV)

Long ago, at many times and in many ways, God spoke to our fathers by the prophets, but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world. (Hebrews 1:1-2 ESV)

Mechanics of Salvation - the Blood
The blood shall be a sign for you, on the houses where you are. And when I see the blood, I will pass over you, and no plague will befall you to destroy you, when I strike the land of Egypt. (Exodus 12:13 ESV)
If you address as Father the One who impartially judges according to each one’s work, conduct yourselves in fear during the time of your stay on earth; 18 knowing that you were not [a]redeemed with perishable things like silver or gold from your futile way of life inherited from your forefathers, 19 but with precious blood, as of a lamb unblemished and spotless, the blood of Christ. (1 Peter 1:17-19 NASB)

Provision of Sacrifice
And the LORD God made for Adam and for his wife garments of skins and clothed them. (Genesis 3:21 ESV)

And Abel, he also brought of the firstlings of his flock and of the fat thereof. And the Lord had respect unto Abel and to his offering: but unto Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell. (Genesis 4:4-5 KJV)

By faith Abel offered to God a more acceptable sacrifice than Cain, through which he was commended as righteous, God commending him by accepting his gifts. And through his faith, though he died, he still speaks. (Hebrews 11:4 ESV)

And Abraham lifted up his eyes and looked, and behold, behind him was a ram, caught in a thicket by his horns. And Abraham went and took the ram and offered it up as a burnt offering instead of his son. (Genesis 22:13 ESV)

By faith Abraham offered Isaac when he was tested. The one who received the promises was offering his only son. He had been told concerning him, Your legitimate descendants will come from Isaac. He figured that God could even raise him from the dead. So in a way he did receive him back from the dead. (Hebrews 11:17-19 CEB)

Your lamb shall be without blemish, a male a year old. You may take it from the sheep or from the goats, and you shall keep it until the fourteenth day of this month, when the whole assembly of the congregation of Israel shall kill their lambs at twilight. (Exodus 12:5-6 ESV)

The next day John seeth Jesus coming unto him, and saith, Behold the Lamb of God, which taketh away the sin of the world. (John 1:29 KJV)