help...

so my boyfriend and I have had sex but we don't much because I'm a Christian and it goes against my religious views. but I love my boyfriend anyways. his brother just got a trashy girlfriend and they have sex all the time and now my boyfriend bothers me about it all the time. what do I do? do I keep saying no or just do it anytime and get further away from God? I know this is a hard optic because of religion and sex but I need some help and all my friends give me the same answer