2 Hereby know ye the Spirit of God: every spirit that confesseth that Jesus Christ is come in the flesh is of God: 3 and every spirit that confesseth not Jesus is not of God: and this is the [spirit] of the antichrist, whereof ye have heard that it cometh; and now it is in the world already.
4 Ye are of God, [my] little children, and have overcome them: because greater is he that is in you than he that is in the world. 5 They are of the world: therefore speak they [as] of the world, and the world heareth them. 6 We are of God: he that knoweth God heareth us; he who is not of God heareth us not. By this we know the spirit of truth, and the spirit of error.
Matthew Henry's Commentary on 1 John 4:2-6
Commentary on 1 John 4:1-6
(Read 1 John 4:1-6)
Christians who are well acquainted with the Scriptures, may, in humble dependence on Divine teaching, discern those who set forth doctrines according to the apostles, and those who contradict them. The sum of revealed religion is in the doctrine concerning Christ, his person and office. The false teachers spake of the world according to its maxims and tastes, so as not to offend carnal men. The world approved them, they made rapid progress, and had many followers such as themselves; the world will love its own, and its own will love it. The true doctrine as to the Saviour's person, as leading men from the world to God, is a mark of the spirit of truth in opposition to the spirit of error. The more pure and holy any doctrine is, the more likely to be of God; nor can we by any other rules try the spirits whether they are of God or not. And what wonder is it, that people of a worldly spirit should cleave to those who are like themselves, and suit their schemes and discourses to their corrupt taste?