Without religion you wouldn't have extremists, and you certainly wouldn't have wars and terror attacks based around such extreme prejudices and intolerance; people would go back to hating eachother for having difference culture and fighting over resources instead
I don't like religion because it essentially uses fear and scare tactics to trick & force people into doing what it/the church wants- just like any other dangerous cult movement. The trouble with the major religions is that they have been going for so long & grown so large they are accepted much more widely as being 'right' or 'safe', vs much newer religions like scientology which anyone can see is just a money making scheme ( see: put a person in cold water and slowly raise the temp until they boil to death, or throw them in boiling water and they'll jump straight out ).
Then there's the hypocrisy...
( see also: richard dawkins video posted earlier )
'Do as we say, or else' essentially. If you want to believe in some higher power, then fine, but people really don't need to be told how to behave and worship, they can do that on their own terms and in their own way, without being effectively threatened into it, if they really must.
You'd think in this day and age people would be strong minded and intelligent enough to see the world for what it is, and enjoy it for what it is, rather than preferring to be told what to think and do because they aren't capable of living a good life on their own...