Well, to me, religion must involve faith of some kind. So, I think it must involve a God of some sort. I think I can have a set of morals that I choose to follow that defines how I live my life, but unless that also includes a belief in some unseen power which requires faith, I don't see it as a religion.
I think it would go some way towards the right direction if - as far as society is concerned - religion was defined simply as a system of belief. In this way one philosophy, classed as secular, would not be seen as fairer or more neutral than a theistic belief.
I believe this is what the word means in the phrase "freedom of religion" - freedom of everyone to believe what they will (theistic or atheistic) and to worship/act out that belief so long as it does not violate the rights of others.
of course, from a personal point of view, religion is much more than that. But it is *that* too.
In keeping with the last post, I propose that atheism qualifies as a religion, and thus should not be favored by the government over other religions.
I am not so much concerned about the people who personally question or disbelieve the existence of a Supreme Being as I am about those who so zealously oppose any form of religious expression that they interfere with the religious freedom of the people. Such atheists and agnostics, although staunchly opposed to religion, religiously preach their bizarre agenda of intolerance. They worship themselves - "It's about MY rights in MY public places, and how dare you tell ME anything about a God?"
Sorry for the rant.
Religion is the overriding set of principles in one's public and private life. I may call myself a Christian, but if I decide to work on Sunday because it pays more, rather than worshipping God, I make wealth my religion, my highest personal priority.