Parents, or anyone shouldn't force their beliefs on another person. They are just that... beliefs, you can't force people into them no matter what you may think. Religion is a matter of opinion, it isn't something you should be born into which seems to be the way it is now.

If you really don't believe in what you're doing then just tell that to your mother. And whatever you do, don't say you think it's a waste of time. Explain why you don't want to go anymore, otherwise she may not respect your decision.