How did three callers realize they had been under false teaching?
The three callers realized they had been under false teaching by searching the Scriptures for themselves. They asked what the book says, and when they could not find that teaching in the book, they recognized it as false. Their realization came from examining Scripture, not from any teacher opening their eyes.
Les explains that he had three phone calls in a row from people in a particular denomination he regards as way out in left field, though he refuses to name it. The callers came from different parts of the country, and each one said, in effect, that their eyes had been opened and they never realized they were under such false teaching. Les clarifies that he did not open their eyes; rather, they did what he tells people to do—ask what the book says. By searching the Scriptures, they discovered they were under a lot of false doctrine, because they could not find it in the book.
But have renounced the hidden things of dishonesty, not walking in craftiness, nor handling the word of God deceitfully; but by manifestation of the truth commending ourselves to every man’s conscience in the sight of God.