John Gill emphasizes the critical importance of acknowledging Jesus as the Christ, the true Messiah foretold by the prophets. He argues that denying Jesus' messianic identity is the greatest lie, as it contradicts the undeniable truth supported by Jesus' own declarations, the testimonies of the apostles, and divine affirmations. Gill warns that those who reject Jesus in any of his roles—prophet, king, or priest—are not only liars but also antichrists, opposing the very essence of the Christian faith. He highlights that even the devil recognizes Jesus as the Christ, making those who deny Him the worst of deceivers. The sermon serves as a strong reminder of the necessity to uphold the truth of Christ's identity and the implications of denying it.

Ver. 22. Who is a liar, but he that denieth that Jesus is the Christ?.... Or that very Christ, and true Messiah, who was spoken of by all the prophets, since the beginning of the world, and so much, and so long desired by the Old Testament saints: he that denies that Jesus of Nazareth is the Messiah of the prophets, is not indeed the only liar in the world, but he is the greatest of liars; this is a consummate lie, being opposed to a glaring truth, to a fact clear an indisputable; and which rests not merely on the testimony of Jesus, who is truth itself, and who, in express words, more than once, declared and asserted himself to be the Christ; but all the characters of the Messiah, everything that is said of him in the Prophets, meet in Jesus, and the miracles which were done by him are flagrant proofs and undeniable evidences of his being the Christ of God; and all the apostles believed, and were sure that he was Christ, the Son of the living God: to which may be added the testimony of John, who was sent, and came to bear witness of him, and did; and who was a prophet, and a man of great probity and integrity. But there was a greater witness than he; even God himself, by a voice from heaven, bore a testimony to him; and angels, at his incarnation, declared him to be the Saviour, which is Christ the Lord; yea, the devil himself, who is a liar, and the father of ties in other things, knew and owned Jesus to be the Christ; so that those that deny him are the worst of liars, even worse than the devil himself. This may have regard not only to the Jews, that deny Jesus to be the Messiah, but chiefly to such who went by the name of Christians; who denied either his proper deity, or real humanity, as Ebion and Cerinthus, which was denying him to be the God-man, the Mediator, and Messiah; and is true of all such that deny him in any of his offices, or in things relating to them, as his Gospel, and any of the peculiar doctrines of it, delivered by him, and so deny his prophetic office; or any of his ordinances, institutions, and appointments, as lawgiver in his house, and King of saints, and so deny him in his kingly office; or reject him as the alone Saviour, joining their own works with him, in the business of salvation, and oppose his sacrifice and satisfaction, and despise his imputed righteousness, and so deny him in his priestly office. Now these are some of the liars, and these some of the doctrinal lies, which are not of the truth, as in 1Jo 2:21. He is antichrist that denieth the Father and the Son: that denies the Father of Christ to be the Creator of the world, but asserts that it was made by angels, as some ancient heretics did; or that the Father of Christ is not the God of the Old Testament, as Marcion; or that denies that God is the Father of Christ, and that Christ is the Son of God; who will not allow that there is any such relation in nature between them; who affirm that Christ is only the Son of God by adoption, or because of his love to him, or because of his incarnation and resurrection from the dead; or that he is not his true and proper Son, only in a figurative and metaphorical sense; that he is not the natural and eternally begotten Son of God, only by office, and as Mediator, and that God is only his Father, as having installed him into an office; or he that denies that these two are distinct from each other, but affirms that Father is the Son, and the Son is the Father, and so confounds them both, and, by confounding both, denies that there are either Father or Son; and all such persons are antichrists, or opposers of Christ.