Snake, did you really think I referred to stuff like Leviticus 20:13 as profound and important beliefs? Belief in God can plainly be profound and important. Details of the Law of Moses that almost no one thinks apply, not so much. (You do know that Christians don't follow the Law of Moses, right?)
You're still suppressing the obvious rational objection to your argument. Again, every way of doing morality can lead to bad results. Therefore it's plainly a bad argument to infer from a few examples that you have shown one system is worse than another. Many experts understand Kant to imply that we should never lie even to save a life, which you might find stupid. Many experts interpret Mill to imply that it's OK to kill an innocent man to set an example, which is also generally frowned on. In practice, some of the worst atrocities of the 20th Century, quite possibly the worst of all time, were done in the name of reason and science, not theism, by perhaps the most advanced culture of reason and science at the time. Does any of that disqualify reason and science as bases for morality? As long as you ignore this basic flaw in your thinking, something you should have recognized without it being pointed out, you're suppressing reason to protect your preferred beliefs.
To work this out another step or two, you may want to argue that real or good or true reason and science don't lead to bad results. If so, then you need to allow that a similar principle may apply with religion, that real or good or true religion may not lead to bad results either--it may lead to the most wonderful results, as religion sometimes does. And regardless of how that works out, you would need to show that even if we can tell at the time what's real or good or true reason and science, which we obviously can't always do (look at the history), that even the best of it doesn't have a significant risk of leading to worse results over time. That isn't as obvious as you may imagine. (There's no reason to assume, except as a matter of faith, that reason, science and morality are ultimately happy partners--it could be quite plausibly be that the opposite is true in various ways.) And then you still need to show that in practice your alternative produces better results now, on the whole, all things considered.
If you can't do this--if you haven't already done it--then you have no rational ground to so confidently oppose religion. I'm pretty sure you haven't done it, because those are still unsettled issues among experts, and the evidence is hard to interpret. And that should matter to you. Religion has been a deep part of humanity for as long as we know of, and is of great value to many. It's foolish and arrogant to attempt to sweep it aside on the basis of such thin reasoning and evidence about the actual results. If you see some particular religious belief such as opposition to homosexuality as harmful, that can obviously be fought without trying to fight religion as a whole, and probably more effectively. Many religious people would join you, for religious reasons.
Speaking of thin reasoning and evidence, Sam Harris would do better to stick to neuroscience. Like other leading loudmouths of atheism, he really doesn't know what he's talking about when he strays into fields he wasn't trained in and has only studied from an ill-willed perspective.
You appear to vaguely appeal to conscience or some similar universal moral sense as part of your better alternative. As pointed out before, there isn't anything conscience can't be molded to approve of. History shows what we may regard as universal moral sense has been anything but. If you really think that's a better alternative somehow, you have a lot of work to do to make the idea even plausible, let alone to establish it to the point that it can be accepted with confidence.
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