Matthew 7:16-17

Beware of the false prophets, (teachers) who come to you dressed as sheep (appearing gentle and innocent) but inwardly are ravenous wolves. By their fruit you will recognize them (that is, by their contrived doctrine and self-focus). Do people pick grapes from thorn bushes or figs from thistles.

When we build our knowledge of the Bible, we build up wisdom for understanding the Word preached. We need to be skillful and wise to sound doctrine and teachings to keep to the path of Faith. Not everything we hear is worth listening to, and we should filter according to the inward witness and the Word of God.