17 so every good tree doth yield good fruits, but the bad tree doth yield evil fruits. 18 A good tree is not able to yield evil fruits, nor a bad tree to yield good fruits. 19 Every tree not yielding good fruit is cut down and is cast to fire: 20 therefore from their fruits ye shall know them.
Matthew Henry's Commentary on Matthew 7:17-20
Commentary on Matthew 7:15-20
(Read Matthew 7:15-20)
Nothing so much prevents men from entering the strait gate, and becoming true followers of Christ, as the carnal, soothing, flattering doctrines of those who oppose the truth. They may be known by the drift and effects of their doctrines. Some part of their temper and conduct is contrary to the mind of Christ. Those opinions come not from God that lead to sin.