Not sure RIP is a specifically religious sentiment. I can't see a problem with people believing whatever they like, if it gives them some comfort then so be it. My problem with religion in general is that if you look at the teachings on the one hand, and some of the stuff that has been done by alleged adherents on the other, it is very difficult to reconcile the two. Look at some of the truly barbaric behaviour carried out in the name of Christianity or Islam as just two examples. Thou shall not kill. A commendably unequivocal instruction, but not seen as an obstacle by various Popes urging their followers to go and murder muslims in the crusades. So not sure religion in and of itself is an issue, more the way people have twisted and manipulated it to their own ends.