Once upon a time, G.K. Chesterton received an anonymous letter asking how he could believe Christianity was exclusively true when the world was full of other religions that also claimed to be true. The letter was simply signed “Free Thinker.” The following is a copy of Chesterton’s response.
Dear Former Thinker,
The vulgar modern argument used against religion, and lately against common decency, would be absolutely fatal to any idea of liberty. It is perpetually said that because there are a hundred religions claiming to be true, it is therefore impossible that one of them should really be true. The argument would appear on the face of it to be illogical, if anyone nowadays troubled about logic. It would be as reasonable to say that because some people thought the earth was flat, and others (rather less incorrectly) imagined it was round, and because anybody is free to say that it is triangular or hexagonal, or a rhomboid, therefore it has no shape at all; or its shape can never be discovered; and, anyhow, modern science must be wrong in saying it is an oblate spheroid. The world must be some shape, and it must be that shape and no other; and it is not self-evident that nobody can possibly hit on the right one. What so obviously applies to the material shape of the world equally applies to the moral shape of the universe. The man who describes it may not be right, but it is no argument against his rightness that a number of other people must be wrong.