He is warning us to be on guard lest we be carried away by the error of lawless men.
These are men who blaspheme where they have no knowledge. They will be destroyed like wild animals. They have eyes full of adultery and never cease from sin. Keep in mind that adultery is the equivalent of idolatry in Scripture.
It is through His Spirit within us that gives us faithfulness to obey His Torah that grant us entrance into His eternal kingdom