You are a creature of extremes, Brother Thomas.- Becket
That we are.
Most AS people I've seen online are like our brothers and sisters among the normals, the hardcore science nerds: angry, burned-out atheists and agnostics. "I want hard proof so without it your religion is as real as Santa Claus!" (These seem to include angry goth teens, who showed up at the only support-group meeting I ever went to.)
(TV's Bones, the best poster girl for AS, is one of them, playing off any-time-now love interest Booth's nice Irish Catholic cop. Nice to see religion shown as normal.)
Then there's me and the other founder of Finding Center, who fall into the pattern a churchgoers' message board suggested, and I agree, that we might be happy with the comforting routine (rituals), clear-cut rules and strong culture for a sense of belonging (the Catholic Church: when you're here, you're family, you might hope) of the liturgical "high" churches (Roman Catholic and Anglican/Episcopal, particularly the old-fashioned versions of them, or Greek Orthodox), Orthodox Judaism, Islam or Tibetan Buddhism.
Then there are those in those churches and faiths, and those in conservative Protestant ones (PCA Presbyterian, Wisconsin Synod Lutheran, Southern Baptist, Assemblies of God etc. - not necessarily a lot of ritual but strong, clear rules) you suspect are undiagnosed AS people, preaching to everybody trying to force their beliefs on you, talking at you not to you. (Very evident online as it's a natural social center for us with AS.)
AS spiritual strengths and weaknesses
So as you can see, just like normals we're not all alike. But what has all this in common? Lots.
We like things black-and-white clear so in a way we're natural-born fundamentalists. Hardcore atheism takes blind faith (against inferring God's existence) so it fits the pattern!
Some of our shared strengths:
We like having a strong moral code. We're often honest to a fault (lack tact), often making us the world's worst liars. And part of that moral sense, which goes against the new pop-culture image of us as selfish, is we have a strong sense of fairness/social justice because we've often been treated unfairly. (Some say a fault of nerd social circles is they bend over backwards to include everybody so problem people get out of hand, or we're too tactful trying to spare somebody's feelings.)
Like I said, the fundies of many faiths including no faith trying to clobber you to fit their worldview. A common mistake AS people make when trying to understand and relate to normals is when you learn a few facts and rules about something in normal culture, you try to win the normals' respect by mastering the rules, becoming the "rule police," which of course doesn't work with most people, at least those you probably want to become closer to.
Related to that is the mistake I think some unaware AS people make, when religion becomes one of their special interests, of getting disillusioned with their one true faith of the moment and switching to another, leaving behind a lot of hurt feelings. The Internet is littered with a lot of this.
And although we're not guilty of these things unless we know they're wrong and do them on purpose (using the AS as an excuse for example), sometimes we are rude and selfish.
Scrupulosity (intense guilt for no good reason) is something a lot of us suffer from, from having naturally delicate consciences and possibly made worse by not having enough of the right moral training to know what's important and not sweat the small stuff.
Things that work or not
Churches that have private confession of sins and spiritual counseling/direction can be a, yes, godsend to AS people but you have to remember it's not therapy (sometimes "therapy" is not therapy for that matter); few ministers are psychologists but they're trained to spot problems too big for them to handle and refer you to somebody qualified to deal with them.
Back to "when you're here, you're family," wanting to belong. Will glomming onto a religious culture, your family's or somebody else's, get you that? Maybe, maybe not. Possibly by trial and error you'll find a way to make it work. But cultures often don't like their wannabes, whether the wannabes are AS or normals. Don't look like you're trying too hard (see above on being the rule police) and you should be all right.
AS ways of being religious are out of fashion in our ex-Protestant culture (most normals think they're childish), unless the ways belong to groups considered righteous because they were treated badly historically (Jews) or are considered exotic and non-threatening (Tibetan Buddhism). You'll be patronized, pathologized or worse. ("Well, isn't that special? You need that. I don't need a crutch.") Hang in there. (And don't tell people you're a martyr. Self-pity's not cool.) The normals in those faiths have to live with it too; don't p*ss them off by trying too hard to imitate them (rule police) and you might make a friend or two.
So why do I think there are so many atheist and agnostic AS people? My guess is they're right that mainstream American churches - liberal mainline Protestant, suburban Vatican II Roman Catholic, rich evangelical - have nothing for them. (Lesson many of us learn the hard way: most people you know don't care about you.) Those churches are all about the American civic religion, moralistic therapeutic deism: the upper middle-class normals patting themselves on the back for being such wonderful people. (And they think we're stuck on ourselves!)
If there isn't a God, religion is not a waste because of the good you and your fellow man do for each other and the good you leave behind when you die. Also consider a form of Pascal's wager (basically give faith a chance). The right kind of religion teaches you to be responsible for what you do. And as I counseled an ex-fundy online who'd had a nervous breakdown and lost his faith, just go to the only church in your one-stop town (which happened to belong to a liberal mainline denomination) every Sunday without fail and leave a dollar in the collection plate. Never mind truth claims for now. Then take it from there.
If there is a God, the fact of evil in the world (why AS, why me?) is something neither believers nor nonbelievers can explain, but he knows, cares about and feels for you and wants you to know and love him and be happy with him for ever after.
I recommend to all the famous first three lines of the Serenity Prayer.
Finally as you can see I've tried not to push any religious truth claims or my own special interests here. That said, the Catholic Church is Western civilization, and the King James Bible and old Book of Common Prayer are English civilization. Whether you believe a word of it or not, for your own education/cultural enrichment listen to Gregorian chant and religious classical music at a service or concert or using some recordings, and have those books or Web bookmarks, including the Catechism of the Catholic Church, at least as references.