“False doctrine does not meet men face to face, and proclaim that it is false. It does not blow a trumpet before it, and endeavor openly to turn us away from the truth… It approaches us secretly, quietly, insidiously, plausibly, and in such a way as to disarm man’s suspicion and throw him off guard. It is the wolf in sheep’s clothing, and Satan in the garb of an angel of light.”
— J.C. Ryle
Jude 1:4 For there are certain men crept in unawares, who were before of old ordained to this condemnation, ungodly men, turning the grace of our God into lasciviousness, and denying the only Lord God, and our Lord Jesus Christ.
2 Corinthians 11:13-15 For such are false apostles, deceitful workers, transforming themselves into the apostles of Christ. And no marvel; for Satan himself is transformed into an angel of light. Therefore it is no great thing if his ministers also be transformed as the ministers of righteousness; whose end shall be according to their works.
Matthew 7:15 Beware of false prophets, which come to you in sheep’s clothing, but inwardly they are ravening wolves.