The above image was actually never supposed to see the light of day. It is a personal image I made for myself while fighting temptation. I looked back over all my past sins and took note of how, rather than appealing to God, I said "let my will be done". I had the power to not sin, and yet I sinned anyway.
And this is exactly what the Bible says. If we say we are without sin, we are liars (1 John 1:8), and yet in 1 Corinthians 10:13, we read "No temptation has overtaken you except such as is common to man; but God is faithful, who will not allow you to be tempted beyond what you are able, but with the temptation will also make the way of escape, that you may be able to bear it." If I was able to bear sin, and yet I did not bear sin, what does that tell us? We have free will.
Free will is a surprisingly controversial topic even within Christianity. Although there is a minority within the faith who believe it does not exist, or exists in a significantly limited amount, Christians generally believe in what is called "Libertarian free will". That is, within physical constraints, we are able to freely choose from a number of moral options. This, of course, explains how evil could exist in an initially "very good" world (Genesis 1:31) created by a God whose works are perfect (Deuteronomy 32:4).
But atheists don't often like this concept. In their mind, if God gave us free will, God is evil, because He knew we would use free will for evil. But as I pointed out, every time we use free will for evil, we could have used it for good. Sinners do not have to sin. When we sin, God cannot be blamed, because all He did was give us the ability to choose.
"But He still gave us the ability to choose evil", the atheist might object, as if that shifts responsibility one inch. In reality, the responsibility for any choice lies with the one who makes it, not the one who gives it. What's more is that the whole intention of free will is to maximise the choice of good. Without free will, we would be robots. With free will in existence, it becomes polite to thank a bus driver for nothing more than driving a bus. But who says thank you to the bus itself? The bus doesn't think, or feel, it just does what it's told. Effectively, without giving us the choice to do evil, God couldn't have given us the ability to do real good.
It boggles my mind that this discussion even needs to happen. Free will is a beautiful gift from God, and when we abuse it, it is entirely our responsibility. Let us therefore repent of the folly, rejoicing in the fact that God does not immediately punish us for our sin, as He would be justified in doing. Rather, He chose to forgive our sins through our faith in the death and resurrection of the Lord Jesus Christ. Stop trying to blame God for your evil and instead thank Him for His goodness.