If God is all knowing He would have known that humans would sin. So why did He create them?
Two counter questions:
- Before you were born your parents knew that you would disobey them and be bad from time to time. Still, they desired to have you.
- Before you got married you must have known that your spouse would argue with you from time to time, yes, even disappoint you! Still, you got married!
“If a thing is free to be good it is also free to be bad, and free will is what has made evil possible.
Why, then, did God give them free will?
Because free will, though it makes evil possible, is also the only thing that makes possible any love or goodness or joy worth having.
Badness is only spoiled goodness.”
↑C.S. Lewis, Mere Christianity (1952; Harper Collins: 2001) 47-48.