The source of false doctrine...

What difference would it make if we seriously thought about the origins of false doctrines?

It is vitally important to realise that heresies do not originate in the minds of men and women. Ultimately heresy originates with the devil.

When the apostle Paul takes the Corinthian church to task for tolerating false teachers he compares their approach to the deception of Eve by the serpent (2 Cor. 11:3). But the deception in the Garden is more than a useful illustration. The super-apostles at Corinth are the servants of the devil disguising themselves as apostles of Christ.

Similarly Paul warned Timothy about “deceitful spirits and the teachings of demons” (1 Tim. 4:1), and of false teachers who are caught in the snare of the devil (2 Tim. 2:24-25). After all the devil is the father of lies (John 8:44). One of the English Puritans said that the devil never lets the wind blow for too long in the same direction.

Invoking this category to account for theological aberrations is hardly a way to win friends. However, to ignore it is to close our eyes to the clear testimony of Scripture concerning false teaching.

Wayne Grudem has provided a helpful reminder on this point:
After reading such verses [2 Peter 2:1; Jude 3-4], we might wonder if any of us have the same kind of heart for purity of doctrine in our Christian organisations, and the same sort of sober apprehension of the destructiveness of false doctrine, that the New Testament apostles had in their hearts. If we ever begin to doubt that false teaching is harmful to the church, or if we begin to become complacent about false doctrine, thinking that it is fascinating to ponder, stimulating to our thoughts, and worthwhile for discussion, then we should remind ourselves that in several cases the New Testament specifies that the ultimate source of many false teachings is Satan and his demons.

In Beyond the Bounds, p. 342