It is not merely true that a creed unites men. Nay, a difference of creed unites men - so long as it is a clear difference. A boundary unites. Many a magnanimous Moslem and chivalrous Crusader must have been nearer to each other, because they were both dogmatists, than any two agnostics. "I say God is One," and "I say God is One but also Three," that is the beginning of a good quarrelsome, manly friendship.

The collected works of G.K. Chesterton (ed. Ignatius Pr, 1987) - ISBN: 9780898701470