Yeah, I call myself 'agnostic' too, for much the same reason. There are others here who prefer 'atheist'. I suspect that most card carrying Christians would call us all 'atheists' (among other things :D ).
My personal theory is that religion evolved as an integral part of many societies from very early in the history of humankind: it was socially functional as a mechanism for passing down important information between generations; as a way of coping with despair at the pointlessness of life; as a device for marking important moments in life; and yes, also as a vehicle for political control.
I am skeptical of whether all the people who profess to believe in it actually do - and BTW I say that as a son of the manse, brought up in the body of the Kirk of Scotland