Every genuine believer has experienced divine enlightenment from Scripture safe-guarding his heart from false teaching. The shining Word will enlighten the believer, exposing the false teaching. The Lord's personal deliverance. He promises to deliver from error those who live a godly life. The evidence of fruit in the life of the teaching one.
Evil lifestyles expose false teachers, and godly living affirms teachers of the truth.
The fruit of the Spirit in the life of the one being taught. Therefore, if a teaching that we are following is from God, it should produce the recognizable hallmarks of the Holy Spirit in our living. Inward discernment by the indwelling Spirit's witness. This implies that we should not automatically assume that all believers' teaching is from God. Yet it also indicates that by virtue of our rebirth, we have the inward ability to discriminate between truth and error.