The Prescription Against Heretics by Tertullian
Chapter XXIX.--The Truth Not Indebted to the Care of the Heretics; It Had Free Course Before They Appeared. Priority of the Church's Doctrine a Mark of Its Truth.
In whatever manner error came, it reigned of course only as long as there was an absence of heresies? Truth had to wait for certain Marcionites and Valentinians to set it free. During the interval the gospel was wrongly preached; men wrongly believed; so many thousands were wrongly baptized; so many works of faith were wrongly wrought; so many miraculous gifts, so many spiritual endowments, were wrongly set in operation; so many priestly functions, so many ministries, were wrongly executed; and, to sum up the whole, so many martyrs wrongly received their crowns! Else, if not wrongly done, and to no purpose, how comes it to pass that the things of God were on their course before it was known to what God they belonged? that there were Christians before Christ was found? that there were heresies before true doctrine? Not so; for in all cases truth precedes its copy, the likeness succeeds the reality. Absurd enough, however, is it, that heresy should be deemed to have preceded its own prior doctrine, even on this account, because it is that (doctrine) itself which foretold that there should be heresies against which men would have to guard! To a church which possessed this doctrine, it was written -- yea, the doctrine itself writes to its own church -- |Though an angel from heaven preach any other gospel than that which we have preached, let him be accursed.|