Because delusion is not healthy for the brain. I would put the religious
>belief in a god
on the same boat as the atheist
>belief in no god
http://www.merriam-webster.com/dictionary/atheist
Both hinge on a belief that they are correct. However, the only logical answer one can come to would be to say "I don't know" when asked "is there a god?" There is no proof either way. All atheists are able to do is discount religious dogma, but that is not he same as disproving god. All religions can be 100% wrong, but that doesn't disprove god.
So, back to my main point. Delusion is a belief in a false idea. You are living under delusion. This delusion stems from the dichotomy of knowing that there is no known answer, and yet choose an answer anyway. That isn't healthy for the brain so I do not think it is a force for good.
Charities already exist that are not religious based, and I didn't need religion to tell me to treat other people with respect and not to hurt/kill anyone.