This is tough. Why do you think you’re friends will leave you because of this? Are they very religious or will they just be upset that you lied to them? If you do tell them, maybe don’t say that you always do it but that you recently did it a couple times so it won’t be like you have been lying for a while. And think about it this way, if your friends say they don’t do anything like that either, maybe they feel the same way and are hiding that stuff just like you are? If you are content with hiding it, you can do that unless you feel down about yourself for lying. If you feel very down about it, I would tell them and if they leave then maybe they were just bound to leave at some point? Do whatever makes you feel the best about yourself!