Religious claims conflict so radically that they cannot all be true. For instance, the Christian doctrine that Jesus is God incarnate is blasphemous to the Muslim, and to accept this doctrine is to commit the sin of shirk—ascribing partners to Allah. Or take the historicity of Jesus’ resurrection as foundational for Christianity. The Hindu would stress that it doesn’t matter whether Jesus rose or not; his teachings still ring true. In these two cases, while both positions may be wrong, both cannot be right. If, as relativism maintains, both A and its opposite non-A are true, then what is false? Such talk negates any logic and reasoning. If someone’s “truth” is the opposite of another’s, then both simply cannot be true.
— Paul Copan, from “True For You, But Not For Me”, p. 30