What kind of a God we have?

In our small circle of Quran researchers, someone, named Aqil Suleimani was questioning our imaginations about God. That is, do we know God in Islam well? And does our definition of God, and what he does, match with Quran?

Do we know God? Or maybe we have wrong assumptions? People say why does God let bad people do whatever they want and murder innocent people? Did Quran say God would prevent such people from killing, murdering and jailing?

Then he asks a question. How does God decide who to save and who to let perish among believers and the Prophets?

Why does God save Abraham from Fire? But he lets people saw Zechariah and kill him? Why did God help Muslims in Badr but did not help them in Uhud? Why didn’t God save people in Ukhdud?

I think he is asking a good question. More examples from me, God lets people behead John. But then he rescues Jesus(according to the Islamic account). He also saves Moses, Noah and their followers. But then he lets corrupt Jews kill several Prophets. We have some sayings from the Prophet Muhammad that God inspires 60 Prophets in a day and they kill them all. Or that God sends a Prophet in the morning, another one in the noon and finally another one in the evening and they kill them all. God does not save them. But according to the Old Testament account, he saves Elias and Daniel. And many many other examples.

This leads us to a question:

Among believers and the Prophets, who does God save and who he lets people kill them? And why? How does God decide who to save?