One of the central issues that Christian theologians have been wrestling with since the Middle Ages is the Problem of Evil. It is based on three assumptions about God:
1) God is omniscient (all-knowing).
2) God is omnipotent (all-powerful).
3) God is omnibenevolent (all-good).
If all three of these assumptions are true, why does evil exist in the world?
However, I don't think this is the central issue with those three assumptions. The Bible itself suggests that they can't all be true, regardless of the place of evil in the world.
Let's assume for the moment that God exists, and that the Bible presents an accurate representation of his character.
The only way to heaven is through faith. This implies that the most important thing in the world to God is that you believe in him and believe that Jesus is divine. If you do not, you are condemned to eternal punishment.
The conflict with the three assumptions comes not in the existence of evil, but in the existence of non-believers.
Does God not know how to convince them he exists? Then he's not omniscient.
Is God incapable of convincing them he exists? Then he's not omnipotent.
Is God unwilling to convince them he exists? Then he's not omnibenevolent.
I think the Bible provides a clear answer to at least one of those questions. Regardless of omniscience or omnipotence, God is clearly not good. In the Old Testament, he sanctions slavery, genocide and the abuse of women and children. In the New Testament, he offers vicarious redemption, the truly twisted idea that I can wrong you and SOMEONE ELSE can forgive me for that, whether you do or not.
There is no problem of evil; there is no problem of non-believers. The Bible resolves the issue quite clearly.