Theology from A Bunch of Dead Guys™

The Heretics
"Though we, or an angel from
heaven, preach any other gospel
unto you than that which we have
preached unto you, let him be accursed"
(Galatians 1:8).

he church was troubled by heretics from the beginning. Before the end of the apostolic era, false teachers were already introducing novel ideas that ate like gangrene at the life of the church. Paul warned Timothy about "Hymenaeus and Philetus; who concerning the truth have erred," overthrowing the fragile faith of early Christians by teaching them that the resurrection of believers was already a past event.
Gnosticism bred heresy in the second-century church, fed by men like Marcion. In the centuries that followed, some of the most notorious heretics were often eminent teachers, such as Arius and Origen.
These early heresies are instructive even today, because they planted the seeds of many false teachings that still endure. The student of church history who has an understanding of these early heresies is better equipped to recognize modern deviations from the truth. Modern apostasy usually mirrors some error from the past.