Believe it or not if it hadn't been for "false doctrine" the New Testament probably wouldn't have been written.
Harold O.J. Brown said in his book, "Heresies: The Image of Christ in the mirror of Heresy and Orthodoxy from the Apostles to the Present (New York: Doubleday, 1984, p.xxiii):
"the history of theology is in large part a history of heresies".
The struggle between heresy and orthodoxy has taken place in every century of church history.
Error, indeed, is never set forth in its naked deformity, lest, being thus exposed, it should at once be detected. But is craftily decked out in an attractive dress, so as, by its outward form, to make it appear to the inexperienced.....more true than truth itself..... . Iraneus, Against Heresies 1:2
Holding fast the faithful word as he hath been taught, that he may be able by sound doctrine both to exhort and to convince the gainsayers. Titus 1:9