Should we try to eliminate religion entirely? Deconvert the world?
These are the big questions making the rounds of the atheist community these days.
I say it depends on what your goals are. Let's say for the sake of argument that the goal is to leave a human-habitable planet with a sustainable human society on it for our descendants. Preferably a free and open society, and not some bizarro soylent-greenish solution like "okay we have enough resources for everyone to live happily until they're thirty, then we have to eat them..."
Given our current globally-interdependent world, creating a sustainable human society/lifestyle will require a great deal of cooperation among all of the peoples of the world.
(This post will be full of unsubstantiated claims and opinions like that one -- please feel free to dispute any or all of them in the comments.)
I think religion can hinder cooperation and understanding among peoples, but I don't think it's necessarily the primary obstacle. And setting out with a goal to eliminate religion can interfere with more important goals.
Consider the goals of freedom of/from religion, separation of church and state, and a free society with a shared secular public sphere. Consider the goal of high-quality public education, which is what allows people to recognize the difference between actual freedom and the slogan "freedom" (and vote for the former in a democracy). All of these are goals where lots of believers can get on board with us.
There's one thing to keep in mind about believers who are political moderates: Just because they're not violent/dangerous/insane, that doesn't necessarily mean they're not attached to their faith. If they get the impression that the ultimate goal of science education (and/or freedom of religion) is to eliminate religion, many will feel threatened and start to sympathize with the theocrats. There's no reason to alienate our allies like that. Keeping crap-masquerading-as-science out of the schools is not some sort of stealth evangelizing for atheism, and it benefits the whole society. People of differing worldviews can coexist and interact in a free society as long as they agree to do so.
Some say that if there were no religion there would be no war. After all, it's easier to convince people to go out and kill other people if they think it's God's will. God kills people all the time, and carrying out his will is -- by definition -- good. And it's easier to convince people to risk their own lives if they think martyrdom leads to paradise, not to true death.
Still, I think that -- even without religion -- the root causes of war would still be there. War is fundamentally about competition over resources.
People who feel confident that they will see their children grow up to be successful adults have little to gain and lots to lose from violence. The most dangerous people are those whose prospects are so bleak that they're better off taking resources by any means, including killing and risking death. I talked about this in my fertility, mortality post. Any human community can be persuaded to get along with any other human community -- regardless of religion -- as long as it's in their interest to do so.
I would argue that the converse is also true: That (regardless of religion) any human community can be persuaded to kill any other human community if it's in their interest to do so. Humans have a remarkable ability to stereotype and make assumptions about any human community they see as "other." It's weird, but while you naturally see that your own community is full of all different types of people, it's nearly impossible to avoid mentally flattening different races and nationalities into cartoon caricatures. Even educated people who know intellectually that foreign societies have the full spectrum of human qualities still have a difficult time feeling on a gut-level "they're more like us than they are different." Actually living in a city where you're surrounded by people of different origins (or living in a foreign society) seems to be the only way to see that people are the same, and even then it's not clear whether you're learning that "people everywhere are just people" or whether you're merely expanding your own community.
The problem (as well as the "adaptive" value) of mentally simplifying other groups is obvious. The belief that "they're like that, they're not ordinary people like us" is what paves the way for the belief that "they can't be reasoned with; we have no choice but to kill them."
I think that the meta-strategy for peace and sustainability is to see to it that the children of every country have a real opportunity to grow up healthy (again see fertility, mortality for details). See to it that every parent has the expectation that all of his/her children will live to adulthood, which makes it so that investing themselves completely in raising a few treasured children well (and not a quiver-full of disposable warriors) is the most attractive strategy.
How does religion play into this? Regardless of what is written in any official holy book, most people are going to act in their best interest. When it's time for war, those who like the scriptures about God killing all the infidels will rise to power, and when it's time for peace, those who prefer the passages about God loving everyone will rise to power. I figure we might as well make friends with that latter group and compare notes with them. They're the ones who are in a position to sway the (political) opinions of the average believer.
Let's look at this in terms of strengths and weaknesses: The advantage that the fascists, racists, fanatics, and theocrats have is that they enjoy lockstep, unswerving, unquestioning obedience from their followers. Their disadvantage? They can't get along with their closed-minded counterparts in any other racial/ethnic/religious group.
For those who want a free, open, secular/pluralistic society it's the opposite: Everybody has an opinion, nobody will unquestioningly follow the leader through right and through wrong. So our weakness is that most of the time we're marching in a bunch of different directions at once. But our strength is cross-cultural cooperation. Every race, creed, and culture has its open-minded people, and by definition their superficial differences aren't a barrier to working together.
If we can agree (atheists as well as people of faith) on meta-strategy, we can start to make progress on how to carry it out. It's easier said than done at every step of the way, though, so we'll see...