Does a person's religion or spirituality really have any effect on making them want to be better people ?

It depends on several things. First, the religion has to correspond with objective moral truth. Second, a person has to commit himself to that religion; only the individual can make himself better (even if it's through letting others help him). Finally, religion isn't about emotions; while emotions can be a great motivator, most of the time becoming a better person is about knuckling down and doing things that are neither easy nor fun. But religion can provide a goal for the kind of person you want to become. The motivation lies in that vision, and not necessarily in the emotions.