Carson on false teachers and discernment

This is from For the Love of God, vol. 1, by D. A. Carson, June 9.

THREE QUESTIONS:

(1) How can you spot a false prophet? The Bible offers several
complementary criteria. For instance, in Deuteronomy 18:22 we are told
that if an ostensible prophet predicts something and that thing does
not take place, the prophet is false. Of course, that criterion does
not help very much if what the prophet has predicted is far into the
future. Moreover, here in Deuteronomy 13 we are warned that the
inverse does not prove the prophet is trustworthy. If what the
ostensible prophet predicts takes place, or if he manages to perform
some sort of miraculous sign or wonder, another criterion must be
brought to bear. Is this prophet’s message enticing people to worship
some god other than the Lord who brought the people out of Egypt?

What this criterion presupposes is a thorough grasp of antecedent
revelation. You have to know what God has revealed about himself
before you can determine whether or not the prophet is leading you to a
false god. For the false god may still be given the biblical names of
God (as in, say, Mormonism, or the christology of Jehovah’s Witnesses).
John’s first epistle offers this same criterion: if what an
ostensible prophet (1 John 4:1 – 6) teaches cannot be squared with what
the believers have heard “from the beginning” (1 John 2:7; 2 John 9),
it is not of God (so also Paul in Gal. 1:8 – 9).

(2) Why are false prophets dangerous? Apart from the obvious
reason, viz. that they teach false doctrine that leads people astray
from the living God and therefore ultimately attracts his judgment,
there are two reasons. First, their very description — “false prophet”
— discloses the core problem. They profess to speak the word of God,
and this can be seductive. If they came along and said, “Let us sin
disgustingly,” most would not be attracted. The seduction of false
prophecy is its ostensible spirituality and truthfulness. Second,
although false prophets may enter a community from outside (e.g., Acts
20:29 — and if it is the “right” outside, this makes them very
attractive), they may arise from within the community (e.g., Acts
20:30), as here — for example, a family member (13:6). I know of more
than one Christian institution that went bad doctrinally because of
nepotism.

(3) What should be done about them? Three things. First, recognize
that these testing events do not escape the bounds of God’s
sovereignty. Allegiance is all the more called for (13:3 – 4).
Second, learn the truth, learn it well, or you will always lack
discernment. Third, purge the community of false prophets (a process
that takes a different form under the new covenant: e.g., 2 Cor. 10 —
13; 1 John 4:1 – 6), or they will gradually win credence and do
enormous damage.