Joseph Benson's Commentary of the Old and New Testaments - 1 John 4:1
1 John 4:1. Because the Gnostics and other heretics, in the first age, to gain the greater credit to their erroneous doctrines, assumed to themselves the character and authority of inspired teachers, John put his disciples in mind, (1 John 2:27,) that they had an unction from the Holy Spirit, by which they were enabled to judge with certainty, both of teachers and of their doctrine. He therefore, in this chapter, commands them not to believe rashly every teacher who pretended to be inspired,... read more
Albert Barnes' Notes on the Whole Bible - 1 John 4:3
And every spirit that confesseth not ... - That is, this doctrine is essential to the Christian system; and he who does not hold it cannot be regarded either as a Christian, or recognised as a Christian teacher. If he was not a man, then all that occurred in his life, in Gethsemane, and on the cross, was in “appearance” only, and was assumed only to delude the senses. There were no real sufferings; there was no shedding of blood; there was no death on the cross; and, of course, there was no... read more