Verse 22. Who is a liar. That is, who is false; who maintains an erroneous doctrine; who is an impostor, if he is not? The object of the apostle is to specify one of the prevailing forms of error, and to show that, however plausible the arguments might be by which it was defended, it was impossible that it should be true. Their own knowledge of the nature of religion must convince them at once that this opinion was false.

That denieth that Jesus is the Christ. It would seem that the apostle referred to a class who admitted that Jesus lived, but who denied that he was the true Messiah. On what grounds they did this is unknown; but to maintain this was, of course, the same as to maintain that he was an impostor. The ground taken may have been that he had not the characteristics ascribed to the Messiah in the prophets; or that he did not furnish evidence that he was sent from God; or that he was an enthusiast. Or perhaps some peculiar form of error may be referred to, like that which is said to have been held by Corinthus, who in his doctrine separated Jesus from Christ, maintaining them to be two distinct persons. -- Doddridge.

He is antichrist. See Barnes "1 Jo 2:18".

He has all the characteristics and attributes of antichrist; or, a doctrine which practically involves the denial of both the Father and the Son, must be that of antichrist.

That denieth the Father and the Son. That denies the peculiar truths pertaining to God the Father, and to the Son of God. The charge here is not that they entertained incorrect views of God as such -- as almighty, eternal, most wise, and good; but that they denied the doctrines which religion taught respecting God as Father and Son. Their opinions tended to a denial of what was revealed respecting God as a Father -- not in the general sense of being the Father of the universe, but in the particular sense of his relation to the Son. It cannot be supposed that they denied the existence and perfections of God as such, nor that they denied that God is a Father in the relation which he sustains to the universe; but the meaning must be that what they held went to a practical denial of that which is peculiar to the true God, considered as sustaining the relation of a Father to his Son Jesus Christ. Correct views of the Father could not be held without correct views of the Son; correct views of the Son could not be held without correct views of the Father. The doctrines respecting the Father and the Son were so connected that one could not be held without holding the other, and one could not be denied without denying the other. See Barnes "Mt 11:27"; See Barnes "Joh 5:23".

No man can have just views of God the Father who has not right apprehensions of the Son. As a matter of fact in the world, men have right apprehensions of God only when they have correct views of the character of the Lord Jesus Christ.

{a} "that denieth" 1 Jo 4:3