I think it is fair to say that some individuals have improved their quality of life by believing in God/s. I have various books about people who were drug addicts, prostitutes, murderers etc, who turned their lives around because this 'god' was real enough to them to motivate them to change. I'm not saying they couldn't have changed without this 'God' but they needed something powerful (and I suppose the claims of Christianity and no doubt other religions offered them hope and love- love from this 'god' and love from the people representing this god.) If I imagine one of them: a drug addicted, knife weilding thug glancing up at the bus that tells him this is all there is so tough shit if you pulled the short straw in life, then I doubt he'd feel motivated in the same way. I'm sure it's a lot to do with how strong a person is mentally and emotionally, but so many people aren't strong or are damaged so if this 'god' has this very good effect on them (you may call it the lesser of two evils) and 'he' is real to them, then it is no wonder they cling to this 'prop' this 'emotional crutch'.
"The eternal mystery of the world is its comprehensibility"
Albert Einstein
Albert Einstein