Of course I wouldn't presume to answer this question, since I am mot betty boop, but I can ask a question or two about the fustian (or is it faustian?) philosopher.
Why would someone ask "If God is omnipotent, how can he be good?" or "If God is good, how can he be omnipotent?"
I've tended to prefer to ask, "Since God is real and since he has revealed himself with integrity to me, how much can I understand about how he is both good and omnipotent?"
Who is being presumptuous, Mills or me?
Aw go ahead, I can take an insult. BTW, I've found that with an attitude of yielding to God (initiator that he is) one can learn some the most interesting things about him in the paradoxes he presents.
Why would someone ask "If God is omnipotent, how can he be good?" or "If God is good, how can he be omnipotent?"
Because he was looking at the state of the world around him, essentially. In brief, what Mill does is he looks around and observes that the world is far from being perfect, and who can really disagree with him on that? So he asks himself, if God is omnipotent and perfectly good, as He is usually regarded to be, why is the world such a mess? Surely a perfectly good being would want to create good, and not evil - why would a being that was perfectly good create evil, as God must have done if He were the omnipotent creator of everything? Surely a being that was perfectly good would want to create good and virtuous people, so why are there so many bad and wicked people about? After all, if He were omnipotent, He certainly had the power to create people who were some other way than what they are, right? Surely a being that was perfectly good would want to bring about justice, so why is there so much injustice in the world? Surely a perfectly good being would not want to cause suffering, so why is there so much suffering in the world, especially when an ostensibly omnipotent being must have had the power to prevent it?
So from that, Mill concludes that you have two choices, really - either God is in fact omnipotent, and He created this world exactly as He wanted it, with all the evil and wickedness and injustice and suffering there is. But in that case, He must be less than perfectly good, given the sort of world He chose to create. Or, God is in fact perfectly good, but is less than omnipotent, and therefore He created the best world he could. But being that He is less than omnipotent - albeit much more powerful that you or I could ever be, naturally - He couldn't create a perfect world, or one that was as perfectly good as He was. And given the choice, Mill opts for a perfectly good, but limited creator, and suggests that most people unconsciously do the same thing as well, through their various rationalizations about why the world and their personal affairs are in such a state.
Who is being presumptuous, Mills or me?
I don't know. Do you still think that omnipotence and perfect goodness can be reconciled?