Guarding Our Hearts
This admonition is in light of the illustration from vv. 7-10 taken from Psalm 95:7-11. The warning here is to those who know the gospel, who affirm its truth but which, because of a love of sin, have not fully committed themselves to the truth they know is real.
This is the real danger of the world around us. There is a way that seems right but is outside of Christ. Instead of listening to those who would draw us away from Christ, we need to seek the truth of His word and any real correction that may come from those within the Body of Christ.