"Do not think I am speaking of one or two men, when I speak of the scandal which a Christian's inconsistency brings upon his cause. The Christian world, so called, what is it practically, but a witness for Satan rather than a witness for Christ? Rightly understood, doubtless the very disobedience of Christians witnesses for Him who will overcome whenever He is judged. But is there any antecedent prejudice against religion so great as that which is occasioned by the lives of its professors? Let us ever remember, that all who follow God with but a half heart, strengthen the hands of His enemies, give cause of exultation to wicked men, perplex inquirers after truth, and bring reproach upon their Saviour's name."
January 1, 1970
https://en.wikiquote.org/wiki/John_Henry_Newman