He now sums up the reason for his sobering warnings regarding those who seduce them.  The tragedy was that these false teachers, who had abandoned all truth and righteousness, did not simply depart into the world to pursue pleasure.  Many of them remained religious, and strove to foist their false doctrines upon the unsuspecting people of God.  John has thus taken time to remind them of the elemental truths of the Gospel which they have received, and here he pronounces himself confident that the true children of God will not be deceived.  This confidence is grounded upon the indwelling of the Holy Spirit within the people of God.  This is the anointing of which he speaks in verse 27.  They needed no man to teach them how to be the children of God, because that grace had already been communicated to them from heaven.  They were partakers of the New Covenant, in which they needed not for every man to teach his brother, saying, “Know the Lord.”  All knew Him, from the least to the greatest, thanks to the Spirit of God, Who had made Christ’s elect people His special temple.  That anointing of the Holy Spirit teaches the child of God everything that is necessary to life and godliness, and can never lead them into any lie.  He takes of the things of Christ, and shows it to His beloved people.  It teaches us to abide in Christ, and thus our affections remain fixed upon the sole object of saving grace, and we refuse to depart therefrom, even at the solicitations of the most subtle heretics.