This response probably won't answer the question thoroughly, but
I don't think there's anyone on earth who can.
Why did God allow evil to begin? Why did God create
Satan, or us, if He knew we would sin?
This question is almost imponderable, because to claim to know
the answer is to claim to be God. The Bible states that in the
beginning, God created the earth, and everything was good. Quite
clearly, God did NOT create evil. Evil entered this world and
tainted God's creation.
So, if God knew that His creation would be corrupted, and that
Satan would rebel against Him, why create them? The question
shouldn't be why, but why not? God defines love. It is from Him
that we understand and feel love. And one fundamental aspect of
love is giving the other person free will. Allowing them to choose
what they want is at the very heart of love; you don't see loving
husbands forcing their wives into submission very often, do you?
God didn't create automatons; He created beings with free will,
with choice. Simply because He knew they would make the wrong
choice doesn't mean He wanted to remove their choice and take their
existence away. A father doesn't kill his son even if he knows the
son is doing wrong.
Free will, like gravity, is a double-edged sword. The same
gravity that allows us to drive cars causes landslides. Free will
results in both glory and evil. If God were to take away free will,
He would be removing glory as well as evil. The most potent beauty
is found not in good deeds that are done robotically, but that are
done with choice.
That's good and all, you may say, but why doesn't God eradicate
evil and suffering right now? Why doesn't He throw Satan into the
lake of fire immediately? Because God embodies justice and
fairness. If He were to judge one person, as evil as that person
may be, He would have to judge everyone, because that is fair. He
cannot simply selectively pick people to judge. And if He were to
judge everyone right now, how many of us would be considered
righteous in His eyes? Very few, that's how many. By allowing this
world to exist as it is, He's giving us time to redeem
ourselves.
Another thing I'll like to point out is the definition of evil.
Without a God who defines what good is, what objective measure can
we use to define evil? As C.S. Lewis put, "A man does not call a
line crooked unless he has some idea of a straight line." So the
existence and classification of evil actually supports the
existence of an objectively perfect entity, i.e. God.
Since God already has foreknowledge of all events, do we
have free will?
Again, the question is, why not? God knows what choices we will
make, but we make them because of who we are, not because God
preordained it.
Many wonders of nature can be explained without God,
right?
I call BS on that. Sure, science can explain how nature works,
but can it explain how all these phenomena came into being? Can
evolution alone create the human being? (Note: I'm NOT denying
evolution's validity, but I'm questioning its ability to develop
the body's immense biological complexity.)
Hope this helped!