The bible teaches Predestination.

PROOF 1

God sees people before they were even formed on earth and the details of their lives are written down in God's book before they even begin.

Your eyes saw my unformed body; all the days ordained for me were written in your book before one of them came to be - Psalm 139:16

So before our lives even began, our days (and everything we do in those days) were written down in the "book".


PROOF 2

People are appointed their roles on earth even before he was born.

“Before I formed you in the womb I knew you, before you were born I set you apart; I appointed you as a prophet to the nations.” - Jeremiah 1:5

This proves that everyone's life was pre-ordained BEFORE they were born.


PROOF 3

There exists a book that was written BEFORE the creation of the world which contains a list of people who go to heaven. If a person's name is not in it, he goes to hell.



...everyone whose name has not been written before the foundation of the world in the book of life - Revelation 13:8

And whosoever was not found written in the book of life was cast into the lake of fire. - Revelation 20:15

Thus, judgement in the future is based on the contents of the "book" that was written in the PAST.

PROOF 4

In several places in the bible (both OT and NT), humans are compared to vessels created by the potter.


He said, “Can I not do with you, Israel, as this potter does?” declares the Lord. “Like clay in the hand of the potter, so are you in my hand, Israel. - Jeremiah 18:5

But who are you, O man, to answer back to God? Will what is molded say to its molder, “Why have you made me like this?” Has the potter no right over the clay, to make out of the same lump one vessel for honorable use and another for dishonorable use? - Romans 9:20-21

Thus some people are better off than others because people's lots in lives are decided by God.

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"But isn't it unfair that some people are predestined to suffer on earth and then end up in hell?"

No. Nobody is created evil but people choose to do evil. God knows what people will do BEFORE they are created. And thus, writes down their lives on the basis of that knowledge.

Some souls are just inclined to evil and will do evil even if they were placed in the best circumstances. And some souls are good and will do good even if they were placed in the worst circumstances.

"What about instances where God changes his mind about not destroying nations when they repent?"

Nations are not the same as individual souls.
God first intended to destroy Nineveh but didn't when they repented. But that sequence of events occur in our timeline or our perception. God knew even before He sent Jonah that Nineveh would repent. But still sent Jonah on his mission because Jonah had to experience it, and the Ninevehians had to experience repentance.

Another example, the nation of Egypt during the time of Moses were the bad guys because of its ruler, the pharaoh. Yet, individuals in Egypt were good or bad, for example, the midwives who saved the Israelite babies. The pharaoh was drowned because of his evil, but Egypt continued to exist, and later God would bless Egypt call Egypt "My people" (Isaiah 19:25).

God knows best.