I guess this is because for me I know I look for a greater meaning in life. Nothing religious or whatever, but I know I want to make my mark on humanity. Life is short, and I might be forgotten as history passes me by, but I want to live knowing that I made an impact in improving the lives of those who live, and who will live on this world.
Call it my religion if you will, but I think the prospect of a better future for mankind is my calling. Without it, I'm just an Average Joe.
If ones religion is helping the Humanity(its called Karma Yoga) then, I believe, one must see the Divinity inside it first or else one will be frustrated and bounded by its imperfections.