“If I profess with the loudest voice and clearest exposition every portion of the truth of God except precisely that little point which the world and the devil are at the moment attacking, I am not confessing Christ, however boldly I may be professing Christ. Where the battle rages, there the loyalty of the soldier is proved. And to be steady on all the battle fields besides is merely flight and disgrace if he flinches at that point.”
Martin Luther, quoted among many other places by https://www.goodreads.com/quotes/657155-if-i-profess-with-the-loudest-voice-and-clearest-exposition