Christianity pretends to believe that God lets Hitlers etc come for he has to avoid interfering with free will

Christianity says that we must have the power to choose evil or good. But it does not really believe it. Christianity says that we are all sinners meaning that we do not have the free will to live a sinless life. So we only have choice in relation to what sins we want to commit. We have no choice about being sinners or not. This implies that God doesn't give us enough free will. A God who refuses to give you the power to live a sinless life but you gives you rein to commit whatever evil you wish after making sure you will sin is a God of evil. The freedom to live a sinless life is not as important to him as making people inclined to commit any sin even extreme ones. The worship of God is the worship of evil.

If God wanted us to have a lot of free will he would have given us the power to live without sin.

He lets us have a bias towards sin that we will give in to and then lets us become Hitlers if we can. So he gives us too much free will of the wrong kind. The free will argument that evil is compatible with God's love is wrong. To worship God is to close our eyes and hearts to his evil.