1)Devotion to and observance of ANY metaphysical belief system
2)serious commitment to something besides metaphysics -- NOTE: religion does not include just Christianity, yet so many people take the subject too personally and too many above posts seem to refer directly (and usually vehemently) to Christianity...makes you think about so-called "free thinkers" who think they're so smart yet seem to be unable to provide correct and objective definitions of "religion".
Confused individuals use religion for suppression and bigotry.
he doesn't believe in God; science is his religion.
Something sinful; comes naturally to humans (despite claims that "people are basically good at heart"). The opposite of love and good. Something in opposition to God's plan for all. A negative or DESTRUCTIVE rather than creative force. Doesn't neccessarily have to be an act; "he had evil in his heart".