Let us never forget that religious earnestness alone is no proof that a man is a sound Christian. Not all zeal is right–it may be a zeal without knowledge. No one is so mischievous as a blundering, ignorant zealot. Not all earnestness is trustworthy–without the leading of God’s Spirit, it may lead a man so far astray, that, like Saul, he will persecute Christ himself. Some bigots imagine they are doing God service, when they are actually fighting against His truth, and trampling on His people. Let us pray that we may have light as well as zeal.
J. C. Ryle (1816 – 1900)