Believers often say that you need religion because life would be pointless otherwise. But how exactly does religion give meaning to life? Looking at the 'great' monotheistic religions (I don't know enough about the others) it seems that they mainly tell people how to live their lives, i.e. they give them rules about family life, how to worship God etc. But that's not really what I would call 'meaning' or 'purpose'. E.g. the purpose of a pair of scissors is to cut things, i.e. an action outside the scissors themselves. We wouldn't normally say that the purpose of scissors is to have two blades and a handle with two holes for stickin your finers in and a screw in the middle for the blades to open etc (= rules for a good pair of scissors). Whereas rules for a 'religious' life do not refer to any purpose outside life itself... unless maybe you assume that sticking to those rules will make people happy, thus turning their life from a mere life into a happy one. But I don't remember the Bible etc. promising anyone happiness.
So is it supposed to be the promise of a life after death that gives 'meaning' to this life?
Other arguments seem kind of circular to me, e.g. 'The purpose of life is to please God.' So what?
Anyway, I'd like to know why religious people think that religion gives meaning to their life and I'd like to hear some non-circular arguments.