1 John 4:1

The apostle, having said that God's dwelling in and with us may be known by the Spirit that he hath given us, intimates that that Spirit may be discerned and distinguished from other spirits that appear in the world; and so here, I. He calls the disciples, to whom he writes, to caution and scrutiny about the spirits and spiritual professors that had now risen. 1. To caution: "Beloved, believe not every spirit; regard not, trust not, follow not, every pretender to the Spirit of God, or every professor of vision, or inspiration, or revelation from God." Truth is the foundation of simulation and counterfeits; there had been real communications from the divine Spirit, and therefore others pretended thereto. God will take the way of his own wisdom and goodness, though it may be liable to abuse; he has sent inspired teachers to the world, and given us a supernatural revelation, though others may be so evil and so impudent as to pretend the same; every pretender to the divine Spirit, or to inspiration, and extraordinary illumination thereby, is not to be believed. Time was when the spiritual man (the man of the Spirit, who made a great noise about, and boast of, the Spirit) was mad, Hos 9:7. 2. To scrutiny, to examination of the claims that are laid to the Spirit: But try the spirits, whether they be of God, Jo1 4:1.

— Matthew Henry's Concise Commentary (public domain)