The Call of Abraham

Now the Lord said to Abram, "Go from your country and your kindred and your father's house to the land that I will show you. And I will make of you a great nation, and I will bless you and make your name great, so that you will be a blessing. I will bless those who bless you, and him who dishonors you I will curse, and in you all the families of the earth shall be blessed." (Genesis 12:1-3 ESV)

The first thing to note is that Abraham was called.
The second thing to note is he was told to leave.
The third thing to note is he was not told where to go.
The fourth thing to note is he was childless.

If  he obeyed, this was promised to him,

1. He will be given land;
2. He will be a great nation;
3. He will be blessed;
4. He shall be a blessing.

By faith Abraham, when he was called, obeyed by going out to a place which he was to receive for an inheritance; and he went out, not knowing where he was going. (Hebrews 11:8 NASB)

And by faith even Sarah, who was past childbearing age, was enabled to bear children because she considered him faithful who had made the promise. (Hebrews 11:11 NIV)

Religion - Bible vs Koran

For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who by their unrighteousness suppress the truth. For what can be known about God is plain to them, because God has shown it to them. For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse. For although they knew God, they did not honor him as God or give thanks to him, but they became futile in their thinking, and their foolish hearts were darkened. Claiming to be wise, they became fools, and exchanged the glory of the immortal God for images resembling mortal man and birds and animals and creeping things.
Therefore God gave them up in the lusts of their hearts to impurity, to the dishonoring of their bodies among themselves, because they exchanged the truth about God for a lie and worshiped and served the creature rather than the Creator, who is blessed forever! Amen. (Romans 1:18-25 ESV)

And if Allah had willed, He could have made you [of] one religion, but He causes to stray whom He wills and guides whom He wills. And you will surely be questioned about what you used to do. (Surah 16:93 Sahih International Version)

And if Allah willed, He could have made them [of] one religion, but He admits whom He wills into His mercy. And the wrongdoers have not any protector or helper. (Surah 42:8 Sahih International Version)

Why are there so many religions in the world?

According to the Bible, the cause is unbelief. People refused to believe in the truth, thus they believed in their own lies. Truth is one, but lies are infinitely many.

According to the Quran, Allah could have made all people with one religion, but he chose not to.

One Language - Bible vs Koran

At one time the whole earth had the same language and vocabulary. As people migrated from the east, they found a valley in the land of Shinar and settled there. They said to each other, "Come, let us make oven-fired bricks." They used brick for stone and asphalt for mortar. And they said, "Come, let us build ourselves a city and a tower with its top in the sky. Let us make a name for ourselves; otherwise, we will be scattered over the face of the whole earth."
Then the Lord came down to look over the city and the tower that the men were building. The Lord said, "If they have begun to do this as one people all having the same language, then nothing they plan to do will be impossible for them. Come, let Us go down there and confuse their language so that they will not understand one another's speech." So from there the Lord scattered them over the face of the whole earth, and they stopped building the city. Therefore its name is called Babylon, for there the Lord confused the language of the whole earth, and from there the Lord scattered them over the face of the whole earth. (Genesis 11:1-9 HCSB)

And We have revealed to you, [O Muúammad], the Book in truth, confirming that which preceded it of the Scripture and as a criterion over it. So judge between them by what Allah has revealed and do not follow their inclinations away from what has come to you of the truth. To each of you We prescribed a law and a method. Had Allah willed, He would have made you one nation [united in religion], but [He intended] to test you in what He has given you; so race to [all that is] good. To Allah is your return all together, and He will [then] inform you concerning that over which you used to differ. (Surah 5:48 Sahih International Version)

Had your Lord wanted, He would have made all people one united nation. They still have different beliefs (Surah 11:118 Muhammad Sarwar Version)

Did God ever create a world with only one language?

The answer from the Bible is "Yes". From Adam to Noah, the world had only one language. But when the people intend to stick together and build a city after the flood instead of spreading abroad, God decided to confuse their tongues so that they could not succeed in building the one world government ahead of its time.

The answer from the Koran is "No". In Surah 5:48, the Muhammad Sarwar version translated as "Had God wanted, He could have made you into one nation" Yusuf Ali translated as "If God had so willed, He would have made you a single people," And the above Sahih International translate as "Had Allah willed, He would have made you one nation [united in religion]". The implication is God had never created a world with one language. The world had many languages from the beginning and God wanted them to "compete with each other in righteousness." In Surah 11:118, God gave another reason why many languages were created, that is, even with one language, they will still fight and quarrel.