To say that Christianity is true and Islam is not, or vice versa, is like saying that physics is true and chemistry is not. You might say that physics underlies chemistry and in a sense has a more profound truth. But chemistry has its own integrity and cannot be replaced by physics. The atheists would say of course that neither is true, only physics and chemistry But the atheists don’t have a monolopy of truth either. You would have thought that the sad history of religions would have taught them that. Confronted with the impenetrable history of the universe let each find a way that works for them.