Let’s define ‘God’ as “a being which is omnipotent, omniscient, and morally perfect.” Consider the following valid argument:

Necessarily, if God exists, then any evil which exists is either impossible to prevent, impossible to know, or morally required.
However, the existence of Adolf Hitler was possible to prevent, known, and was not morally required.
Therefore, God does not exist.

Premise (1) is just the traditional theistic claim that God is by definition omnipotent, omniscient, and morally perfect. One needn’t define ‘God’ in this way but most theists do so. Premise (2) is substantiated on the basis of the following,

Consider Hitler’s parents – they freely chose to attempt to have a child and it turns out they were successful. However, God could have prevented the zygote that would be or was Hitler from existing by preventing the egg and sperm from becoming that zygote. This does not breach the parent’s free will since they cannot freely choose the fusion of the egg and sperm. Moreover, in the actual world, it would have been better without Hitler than with him. That is, a world in which 11 million innocent people didn’t die would be better than one in which they did.

If you are or were a theist, how would you respond to this argument?