Do you mean "religious" as believing in a particular religion or having religious views? That covers a great many people. I would say I am religious, if that is what you mean.
Personally, I don't see religion as a hobby or an interest. I like what greendawn said, that his religiosity comes from a fascination with the spiritual nature of man. I also liked the comment Ichooselife wrote, "Why should beautiful souls have to be obliterated?" There is also my unshakeable belief that justice is real--that there is something True out there.
That is what makes me search out an answer in religion, to satisfy this insistent deeper belief.
All religious behavior is not mercenary; I am sure God knows that. The idea of reward for good/punishment for evil is bare-boned justice--appropriate reward. No wonder it is found in many religions, whether administered by God, gods, karma, etc.
In the beatitudes, Jesus said mercy would be given to the merciful, that those who thirst for righteousness would be filled, the pure in heart would see God, etc. These are the rewards of God, not petting lions or moving into someone else's fancy home after Armageddon. I am certain that Jesus statements are universal, because an appropriate reward for anyone who really loves mercy would be mercy.