In contrast to the heterodox secessionists ( 1 John 2:19), the faithful believers within the community were "keeping the faith." The "anointing" referred to is evidently the Holy Spirit, whom Jesus gives to each believer at conversion ( Romans 8:9; 1 Corinthians 12:13; cf. Luke 4:18; John 6:69; John 14:17; John 14:26; John 15:26; John 16:13; Acts 4:27; Acts 10:38; 2 Corinthians 1:21-22). John said it abode in his readers to teach them and that it was truthful ( 1 John 2:27). [source][source][source]
"Anointing designates something for sacred use." [1][source]
John referred to the Holy Spirit as the anointing, ascribing a teaching role, which is a personal function, to Him. This seems preferable to the idea that the Word of God is the anointing. [2] John previously spoke of Jesus Christ as the life ( 1 John 1:2). The presence of the Holy Spirit in every believer enables him or her to perceive the truth of the gospel and to distinguish it from error ( John 14:26; John 16:13). Of course, some Christians have more perception than others due to God-given ability, Satanic blindness, the influence of human teachers, sin in the life, etc. [source][source][source]