so what youre really saying is that its a contradiction for a god to exist if he only wants good things for humanity, and no matter what the purpose for the creation of the universe was, he can accomplish that goal in absolutely whatever way he wants, including by only doing good things for humanity.
there are more options besides the previous paragraph and atheism. for example, a god who isnt omnipotent. uccisore, in his first post here, even admits that god isnt omnipotent, although only after a little interpretation i will now provide.
god is omnipotent to magically zap whatever he wants in the universe, he can zap a baby into your uterus, water into lsd. but he also exists in a place separate from our universe, with laws that are different from those in our universe (most notably the lack of the passage of time?). in this meta-universe, he is not omnipotent.
uccisore and any christian will tell you that god made the universe for some crazy purpose we cant fathom, and because of that purpose, he is required to damn us with the problem of evil. he does not have infinite power over the execution of this greater mission, or, as you imply, obviously that is a contradiction.
so youve proven that god either is not super-mega omnipotent or purely dedicated to hedonistic human masturbation. that is Not the same as proving that he doesnt exist. in fact i dont even see how it relates to the discussion of whether or not he exists at all.
for me, the thing that disproves christianity is how they say god wants me to believe in all the silly rituals and a book whose entire credibility hinges on rich people from over a thousand years ago, the descendants of which had no problem torturing and burning scientists because of the negative impact of their enlightening. but that has literally nothing to do with my belief in some sort of life-related creator.
lets say for some reason god needs us to learn to treat our neighbor like ourself. if there is no pain, no potential dearth of resources, no discrepancy between ultimate happiness and average happiness, no desperate criminals to ever take revenge on, no inferior people to ever take advantage of, would this really be a good way to teach people to treat their neighbor like themselves? if your math teacher only ever teaches you 1+1=2, have you really learned math?