God's word or human reason?

The apparent errors and contradictions of Scripture are just as they appear - simple errors. It is understandable that a book by hundreds of authors of different knowledge and education has lots of errors and contradictions. Your assumption of a cruel God is just based on such errors. Look at the following example:

1 Sam 15:2 Thus saith the LORD of hosts, I remember that which Amalek did to Israel, how he laid wait for him in the way, when he came up from Egypt. Now go and smite Amalek, and utterly destroy all that they have, and spare them not; but slay both man and woman, infant and suckling

Ok, God commands the genocide of the Amalekites. Their crime was that they defended their territory against the Israelites 200 years earlier. With a strong Israelitic army established under King Saul in 1000 AC, God now saw his opportunity for revenge. That seems to support the idea of a cruel God. But look how the story continues:

1 Sam 15:7 And Saul smote the Amalekites from Havilah until thou comest to Shur, that is over against Egypt. And he took Agag the king of the Amalekites alive, and utterly destroyed all the people with the edge of the sword

Saul obeys God and kills the whole tribe with one exception. To God's dismay, he spares the life of their king Agag. God is enraged and removes his grace from Saul. Agag, the last Amalekite, is eventually murdered by the prophet Samuel. Genocide successfully finished.

But suddenly, 5 years later:

1 Sam 30:1 And it came to pass, when David and his men were come to Ziklag on the third day, that the Amalekites had invaded the south, and Ziklag, and smitten Ziklag, and burned it with fire

The killed Amalekites are very alive and kicking, and probably mighty pỉssed about their neighbor's God's genocide attempts! So you see that the genocide story in 1 Samuel is completely made up. God never gave that command, the Amalekites were never murdered, and the Bible itself confirms this just a few pages later.

When you look at all stories how God killed this family and extinguished that tribe, they'll turn out to be mostly made up by some Bible authors who thought that those stories would contribute to God's glory.

This is a good example how too-literal interpretation of the bible leads to the assumption of a cruel, murderous God and consequently, a God whose character needs to change in order to adapt to the improving human morale standard. But stories of made-up victories and genocides were quite normal in that time, you can also find them in Egypt, Assyrian and Babylonic history. You need to read all stories in their historic context. Wrong literal Bible interpretation can insult God by giving him a Hitler-like character, and can do great damage to Christianity.

Let me address this because I've studied this stuff in astrophysics.

It is correct that our universe can be described as a space-time continuum. That however does not mean that it's possible to arbitrarily move from one time event to another. General Relativity limits the possible paths in the space-time continuum. The limitations depends on the metric of the universe. This is why we have a preferred time direction in our universe, and the future is not determined from a position in the past. Paths that allow a look in the future from the past, and would cause the collapse of the wave function of a future event, are just not possible in our universe.

Of course, there are other universes possible that allow information to travel from the future into the past, and thus the future is determined, all wave functions are collapsed and time travel is theoretically possible. Goedel has described such a universe. But in ours there's an event horizon between future and past that's impenetrable for cause->effect relations.

So, in short, it can not be deducted form General Relativity that the future is determined and free will is impossible.

To summarize the article, “free will” is a perception that people have, but it only exists as a mental experience. The article describes a few experiments in which people claimed to be the ones causing their actions even when it clearly isn’t possible:

In that case, at least, there’s no question that “free will” was a complete illusion.

You also don’t seem to really be addressing what I said about Relativity. The reason we can know that the future is determined isn’t because our actions are the results of purely physical processes; it’s just something about the nature of time itself. Even if our actions were somehow the results of things in the spiritual world that aren’t bound by the laws of causality, our actions themselves still exist at certain points in space and time just like any other event, which means they have all already existed from the moment the universe was created. What causes our actions doesn’t have any effect on this.

Yes, for the reasons mentioned above I disagree with the idea that Relativity demands that the future already exists.

You gave the example of a reference frame in which Adam's disobedience had already happened. Such a reference frame is only possible beyond the time plane _after_ Adams decision. Or more precisely, within the light cone originating from the decision space-time location. The metric of our universe restricts the possible reference frames, you can not have any frame you want. There is no possible space-time path that would connect the moment and place of Adam's fall with a moment and place let's say in the creation week before.

This is not a theological argument in the sense that free will would contradict a determined future. It is a physical argument. Adam's decision did not exist in relation to earlier events. It only existed in relation to later events. In contrary to what your father said in his letter, space-time is not a static continuum where events just exist in an absolute way. The mistake lies in the meaning of 'existence'. The universe is a dynamic continuum where the existence of any space-time event is not absolute, but relative to another space-time event. Existence requires the possibility of a physical path connecting one event to the other.

Of course you could argue that God nevertheless knew Adams decision beforehand due to a miracle. But Relativity does not demand this.

It may be, Smolin surmises, that there exists only one mathematically consistent theory of the universe. If this is the case, we could then derive all events in the universe from the properties of its fundamental elementary particles. (Rather like the 19th century observation that if we knew the current position and velocity of every atom, we could predict the whole future history of the universe.)

What Smolin notes is that if such is the case, "we would have little choice but to become mystics. This would be an even purer mysticism than the anthropic principle because then even God would have had no choice in the creation of the world."

Emphasis added.

Have you thought about the implications of a totally determined future on the sovereignty of God?

Do not forget that God, who never had suffered before Christ's birth, did not value human life at that time the same way we do today.

Today we think different about it, and I suspect that even God now thinks differently. He has repeatedly regretted many of His action, and since the birth of Christ He has withdrawn from any direct actions in the world.

I really think you might not be understanding how this works correctly.

Let’s suppose you’re using the reference frame of someone traveling faster than the speed of light. It’s a very common misconception that something in one of Einstein’s Relativity theories doesn’t allow anything to travel faster than light, but this actually isn’t true; this is explained in this article. For someone traveling faster than light, the direction of time is reversed, meaning that what appears to them as the future would be the past to everyone else, and vice versa.

How do you reconcile what you’re saying about these reference frames not being possible with what’s explained in that article? (That’s actually just a preview of the article, but it explains enough to make it clear that the common idea “nothing can travel faster than light” actually isn’t an accurate description of physics, and that from the reference frame of a stationary observer this would cause effects to precede their causes.)

There are two wrong assumptions here. The first one is that the genocide order means that God has a "Hitler-like character".

God ordered the slaying of the Amalekites in 1000 AC. This order fits into a pattern of similar events at that time. From the point of view of God, He had to compete with other gods of other tribes, and had to show His superiority.

I really think you might not be understanding how this works correctly.

Let’s suppose you’re using the reference frame of someone traveling faster than the speed of light. It’s a very common misconception that something in one of Einstein’s Relativity theories doesn’t allow anything to travel faster than light, but this actually isn’t true; this is explained in this article. For someone traveling faster than light, the direction of time is reversed, meaning that what appears to them as the future would be the past to everyone else, and vice versa.

This is in fact far too weak a condition to deal with the entire universe, since space-time expansion is continually removing parts of the universe from observability by stretching their space-time interval from the Big Bang into space-like ones - but this is certainly accurately the case with the Earth, which has maintained its radius since the Big Bang, and all of which is time-like connected with the Big Bang.