Religion has appeared in every human society I have ever heard of in a splendid plethora of forms, and even in sites of stone age societies there is evidence of ritual and burial which would suggest beliefs about the body after death. How about the theory that religion is adaptive in the Darwinian sense (and passed on by 'meme' a la Dawkins) It promotes group cohesion and cooperation and gives the illusion of control in tricky circumstances, which is presumable good for mental health.
The problems with religions we can all cite ie intolerance to groups holding different beliefs and being moved to violence for these beliefs, are a result generally of the organised power structures that arise when clever people get hold of ideas which give them control over large groups of people. (the same of course is true of non religius ideas such as communism) We are a hierachical species, we gravitate towards groups 'like us' for mutual support, it is not surprising religions grow and become powerful forces and then are manipulated by people who enjoy power and status through those religious structures.
In saying I can see why rural african communities continue to enthusiatically embrace christinity long after most missionaries have gone home I do not of course excuse the huge disservice the catholic church has done to the couse of HIV prevention. However, to be honest in the poorest communities it is a moot (sp?) point as access to condoms is so limited both finacially and culturally. I could rant at length her about the plight of the average rural african woman and her staggering lack of choices, buts thats another thread. I also know that the Bush administration has slashed funding for HIV projects if they include condoms rather than exclusively abstinence, due to pressure from the religious right.
This is where religion matters, not the personal beliefs of very nice liberal minded MNs but the organised beliefs of the relgions on the world stage, and here they are often not only distasteful but in my opinion immoral. This is my line in the sand really with religious believers, I can understand why you are personally religious I can not begin to understand why you would want to sign up to the major world religious organsations which is what you are doing when you join a church etc.
Genuinely, why would you want to say eg I am catholic if you do not agree with the intolerant areas of that religion. It would be like supporting the BNP because you liked their environmental policies. If the thrust of the religious organisation you ahve signed up to is doing bad things, prompting intolerance of eg gays, condom using etc, then by signing up you are supporting these views how ever much you protest you dont believe them yourself.