When you say "Even an atheist must admit that there's a certain satisfaction that comes from helping other people (even anonymously) that really has no limit."

When you say "Even an atheist must admit that there's a certain satisfaction that comes from helping other people (even anonymously) that really has no limit." you imply that theists have a reason to being altruistic (an probably will?) while atheists don't (and probably won't). Altruism and faith are not correlated, hence I disagree to the way you worded that.