ISB ~ 1 John 4 v1

test the spirits:An appeal for spiritual discernment. Readers must distinguish lying spirits, who whisper words of deceit into the ears of the false prophets, from the Holy Spirit, whose voice is heard in the teaching of the apostles (Jn 14:26; 16:13). As a practical test, John proposes that one’s confession of faith—especially in Christ’s Incarnation (1 Jn 4:2)—must measure up to the apostolic gospel to be genuine and true. To confess otherwise is to contradict the Spirit (1 Cor 12:3).

false prophets:The heretics who deserted John’s community (2:19). Both Jesus and the apostles warned of their arrival (Mt 24:11; 1 Tim 4:1; 2 Pet 2:1).