Fair enough, but it should be noted that my tolerance for people who believe in faith is conditional - insofar as oppression of women constitutes a violation of human rights. While this may be a feature of some religious systems, it's not a requirement of them, and I treat it as a human rights issue outside of theist/nontheist. If a theist is not an oppressor of women, then hey, believe in god all you want.
There definitely are non-oppressive theists in the world but that doesn't negate those that are and for clearly spelled out theistic reasons.
Similarly, exposing kids to religion I don't have a problem with in itself, so long as they are also exposed to a variety of alternatives. Which, unless they're closed off from the world, is rather hard to avoid. And, anyway, forcible confinement of children in order to preserve religious belief would, I think, also qualify as a violation of human rights.
I have a problem with it. Nobody knows the whole truth of our existence. If people claim to know they're being dishonest or they're delusional. I think instilling dishonest or delusional ideas in children, about things they simply can not comprehend, is abusive.
As for the retardation of science, sure, some people set out to do that. Too many for my tastes. Now, you could make a case that religion requires this by default (science not generally being amicable to religion) but I think most applications we find of this behaviour has a lot more to do with the individuals involved. We may disagree there, and that's cool.
The most threatening religious attacks on science aren't coming from individuals. They appear to be well organized, at least in Christian and Muslim areas of the world.
But I don't see people believing in a deity as a "cancer", because I don't see where they're obligated, by believing in a deity in any form, to oppress women, enslave children, and retard science. That may happen, and that may happen perhaps as a result of individual religious belief, but belief in a god does not equate to these things necessarily following.
In theory, yes. In practice, the evidence is everywhere.
So in my opinion, which is only my opinion, the actions of individuals within a religion do not necessarily reflect the whole of all its members. All three of your examples, moreover, are caused by intolerance - and since we (presumably) live in societies that offer rights for religious freedoms, then it hardly works to defend against intolerance that leads to the suppression of rights by engaging in intolerance that leads to the suppression of rights.
I'm in no way advocating for the suppression of rights. I'm advocating for conversational intolerance.
So. Where religion violates human rights (or other rights), then the debate can - and should - be held on those terms and, really, when addressing those particulars I don't see bringing god into it as a requirement.
I'd rather fight the disease than the symptoms.
I mean, if you met a theist who didn't oppress women, didn't retard science, and didn't indoctrinate kids - would they still be a cancer?
How would they not allow their beliefs to inform their actions? If they're all of those things and voting for Michelle Bachmann for the next US president, for example, only because she has a personal relationship with a dead Jewish guy, they're a cancer on human flourishing.
* I chose to not address the "inevitable extinction" point with the others, because I think this is a strawman. While some religious people might be pretty eager for doomsday, I don't think this scenario is inevitable and it certainly can't be proved such. I think that's frankly a bit silly.
There's certainly no way to prove the future but I see no way around the following scenario. Do you?
Weaponry development is well funded and will be for the foreseeable future. How long before science produces extinction weaponry that can be easily manufactured? Things that go boom might be a while but I don't see biological taking very long. My guess is 200 years at the outside for backyard production. Regardless, I thinks it's inevitable that the technology will be commonplace.
How many people in the world would push the delete button right now if they could? How many of that group would be doing it for some religious nonsense they've been force fed as fact? How many casual believers would become distressed enough, at some point in their lives, to just "kill them all and let god sort them out"?
As I posted earlier, we could completely eliminate religious beliefs and it still could easily happen. I'd just rather it wasn't guaranteed to happen because someone was deluded into thinking death is better than life.