We are told to earnestly contend for the faith, "to reprove, rebuke, exhort, and them that sin, rebuke before all" (2 Timothy:4:2Preach the word; be instant in season, out of season; reprove, rebuke, exhort with all longsuffering and doctrine.
See All... [1]; 1 Timothy:5:20Them that sin rebuke before all, that others also may fear.
See All... [2]). Surely there is no greater sin against God and His people than to lead astray with false doctrine! —TBC

"Beloved, when I gave all diligence to write unto you of the common salvation [3], it was needful for me to write unto you, and exhort that ye should earnestly contend for the faith which was once delivered unto the saints." —Jude 3