You don't get to advertise all the good that your religion does without first scrupulously subtracting all the harm it does and considering seriously the question of whether some other religion, or no religion at all, does better.
This kind of comment is fairly routine in these debates between atheists and the faithful. One side argues that religion does so much good in the world — they point to all the charity which religious people give (which is, on average, greater than nonreligious people, according to at least some studies). They point to the fact that (again, on average) religious people show up in greater numbers, and stay longer, to help with natural disasters and such.
And then the atheists, or the antireligious people, start pointing out all the terrible things that have been done in the name of religion. The Crusades. Terrorism. The Inquisition. And so on.
And now, we've essentially turned the debate into a math argument — let's add up all the good done, and all the bad, and compare them. Of course, it's not that simple — there is no way to quantify these things, and so it turns into an endless debate, with each side pulling out as many examples as possible, as if that will change anything. It won't — there really do seem to be an infinite number of good things for which religion is responsible, as well as bad. And, I have absolutely no idea which side of the ledger would win out, if we could find a way to measure this.
I'll admit that, without giving it much thought, religion seems responsible for many more big bad things than good (see that list above). But, how you compare the countless acts of small or medium goodness (and badness, of course) with these larger acts — well, I think we can all see that it would be a pretty silly exercise.
More importantly, I think it's an exercise which misses the point. Ultimately, I don't have much, if any, control over whether religion continues in the wider world. Or, what form it will take. All I have control over is whether I will be religious, and if so, how. What kind of religion will I have in my life? And, that would seem to imply that the relevant question is not whether religion, in the largest possible sense, has done more good or bad in the world. The relevant question is whether religion has done more good or bad for me.
I firmly, deeply (one might even say, religiously) believe that I am a happier person because of Judaism. And, I believe just as strongly that I am a better — more moral — person because of Judaism. Not that I am more moral than you are; I am more moral than I would be without Judaism. Judaism has made me, both morally and spiritually, better.
If I were to stop being Jewish — if I were to give up on religion, possibly motivated by all of the truly terrible things which have been done in the name of religion, then it would have almost 0 effect on the wider world. Even if the theoretical absolution of religion would be better for the world, the removal of religion from my own life would be ever so slightly worse for the world, because I would be a worse person without it.
Is it really just that simple? Of course not. Like I mentioned in that earlier post, there is a reasonable argument that religious people like me make it easier for the fanatics to continue with their version of religion. And so, you could argue that I have a responsibility to stop being part of the problem. I don't reject that argument out of hand — I think that deciding to no longer be part of a larger problem, even if the immediate effect is infinitesimally small, is a very important thing to do.
But, I have to weigh that theoretical, minuscule effect against the very real, very significant impact which religion has on me, personally. I can understand, in my head, that I might be, in some indirect way, contributing to a larger problem. But I feel in my guts the positives — I live them, and I see them day by day. And so, while I do acknowledge the validity of the other arguments, there really isn't a debate for me. It's pretty clear to me that the world is, ever so slightly, better because I have religion in my life.