Of all the religious dealies that should be true, I'd nominate Karma any goddamn day of the week, too many vile creatures of the goddamn pit walk all over everything and get away with it, they can't get away with this but they do. Of all of the ones that are more LIKELY to be true, I'd say probably Greek/Roman, because life isn't fair, and half of the Powers That Be purposefully being total cocksuckers would cause that fact to make so much more sense.
...I feel like the reason Christianity and Islam stuff gained most of its traction to begin with was because people like to have Just One face to attribute things to. It's the simplicity, I think-- Monotheism is just easier, and that's why it's so appealing. That's why poster children exist, that's why people subconsciously treat individual employees like they by some means more-or-less are the company they work for, and that's why people say that "Hitler killed six million" and you know for a fact they're saying it like he himself unloaded each and every shotgun shell, threw every lever, conducted every experiment, up 'til the moment you remind them that this wasn't the case, but on a primal level that is the idea they "believe" in, because it's easier to assume things are black and white, that you can always project all your hate, all your everything, onto just one party. Humans like what's easy. Order is a human invention, Chaos rules the world, the only meaning to life that there can ever be is the one that you create. Everyone dies, everyone loves something. Life is Beautiful, and also Terrible. Nihilism is Fact, but that shouldn't be cause for concern, as that doesn't necessarily mean that it is True, for the two of them are fundamentally different on a basic level.