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?

4. Ye—emphatical: Ye who confess Jesus: in contrast to "them," the false teachers.

overcome them—(1Jo 5:4, 5); instead of being "overcome and brought into (spiritual) bondage" by them (2Pe 2:19). Joh 10:8, 5, "the sheep did not hear them": "a stranger will they not follow, but will flee from him: for they know not the voice of strangers."

he that is in you—God, of whom ye are.

he that is in the word—the spirit of Antichrist, the devil, "the prince of this world."