To make my point, we should look to David Mills' Atheist Universe. He chose for his example Stalin and Hitler, which history justifiably regards as evil madmen because of their inhumane tyranny, torture and murder of people who, in the dictators' minds, stood in the way of their goals.
He said, if we conclude the Christian god would create hell to deter behavior he disliked (murder, masturbation, rejecting Jesus and/or the holy ghost, premarital sex, non-missionary sexual positions, homosexuality, etc.), knowing beforehand, as only an omniscient would, the majority of humanity would, as a result, suffer eternal torture, then we would be forced to also label this god as evil and sadistic because he likewise would've inhumanely tortured individuals to accomplish his goals.
Hitler and Stalin tortured/killed millions of innocents, but this god would have tortured BILLIONS if we were to believe everyone who "sins" or isn't a believer in that faith goes to hell. The difference here is (besides the math), once Hitler killed you, your suffering was over, but god tortures you for eternity. Heaven's justice doesn't fit the crime.
Christians may then defend this train of thought by stating their god gave us freewill. They say we control our eternal destiny by accepting or rejecting Jesus as our savior and following his rules. But, again, they invalidate their argument by asserting god is omniscient: He possesses total knowledge of the past, present and future. Thus, the fact the majority of humanity would "forsake Jesus" (and would therefore suffer an eternal roasting) was recognized by god before he chose to create hell, before he chose to create man, before he chose to give man an eternal soul, before he chose to make the eternal destinies of souls contingent upon "accepting Jesus," and before he chose to create a devil to deceive man into forsaking Jesus.
If this god is truly omniscient, as Christians believe, then he would've foreseen his "Master Plan" would be disastrous for humanity. Yet, according to biblical doctrine, he crafted his plan of contingent salvation, so that billions of individuals, whom he brought into existence, would be consigned to eternal damnation. He, therefore, would bear direct responsibility for any suffering. So, if god were existent, I couldn't believe he would create a hell, otherwise he certainly wouldn't be benevolent. And if he were omnipotent then why not create a race incapable of sin? If you're going to blackmail us into worship, then why not just make mindless souls to do your celestial sucking up?
In the New York Times in 1955, Albert Einstein said, "I cannot imagine a God who rewards and punishes the objects of his creation, whose purposes are modeled after our own—a god, in short, who is but a reflection of human frailty. Neither can I believe that the individual survives the death of his body, although feeble souls harbor such thoughts through fear or ridiculous egotisms."
Spoken like a true genius.