" Thus Turks and Christians are of different religions, because these take the Holy Scriptures to be the rule of their religion, and those the Alcoran. And for the same reason there may be different religions also even amongst Christians. The Papists and Lutherans, though both of them profess faith in Christ and are therefore called Christians, yet are not both of the same religion, because these acknowledge nothing but the Holy Scriptures to be the rule and foundation of their religion, those take in also traditions and the decrees of Popes and of these together make the rule of their religion; and thus the Christians of St. John (as they are called) and the Christians of Geneva are of different religions, because these also take only the Scriptures, and those I know not what traditions, for the rule of their religion. "

― John Locke , A Letter Concerning Toleration