I think it's impossible to say if it does more harm than good. Wars and terror campaigns are fought in the names of religion - that's the harm side of it.
The good side is that hundreds of thousands of people carry out good work in the name of their God - they also feel peace of mind, happiness and contentment.
Basically the laws of the land are based on the ten commandments. I was bought up with religious beliefs (not staunch) but said my prayers etc. I don't really believe now but there's still a bit of something there.
On balance I personally think it does more good than harm but a lot of it goes unspoken/unremarked.