On false prophets and the test of fruits. Wesley distinguishes between mere doctrinal error and the corrupt living that reveals a corrupt heart.
Sermon 32 of 44 · 1750 · Matthew 7:15-20
Upon Our Lord's Sermon on the Mount, XII
A passage from the sermon
Beware of false prophets. By their fruits ye shall know them. Inquire then, by what fruit ye may know them. The fruit of false prophets is to be tried by the same rule by which we try ourselves: namely, by the marks of those who are truly converted to God.
Do they win souls to God? Do they bring you to feel God's love? Do they lead you to repentance, to faith, to holiness? If so, they are true ministers of the gospel, even though their words may not be in every point what we should have chosen. If not — though they speak with the tongue of an angel — they are wolves in sheep's clothing.
The full sermon is in the public domain and freely available from CCEL and other archives.