Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world. Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ is come in the flesh is of God: And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God: and this is that spirit of antichrist, whereof ye have heard that it should come; and even now already is it in the world. ~ 1 John 4:1-3

The confession that Jesus Christ has come in the flesh is not an acknowledgment of a historical person named Jesus. Rather, it is the acknowledgment that this man Jesus, was more than a historical figure. He was God manifested in the flesh. It is a confession that speaks of the deity of Jesus Christ. We know this because of the emphasis John places on the deity of Christ throughout the epislte.

John begins his letter by testifying of the deity of Christ.

That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked upon, and our hands have handled, of the Word of life; (For the life was manifested, and we have seen it, and bear witness, and shew unto you that eternal life, which was with the Father, and was manifested unto us;) That which we have seen and heard declare we unto you, that ye also may have fellowship with us: and truly our fellowship is with the Father, and with his Son Jesus Christ. ~ 1 John 1:1-3

Likewise, John ends his letter by testifying of the deity of Christ.

And we know that the Son of God is come, and hath given us an understanding, that we may know him that is true, and we are in him that is true, even in his Son Jesus Christ. this is the true God, and eternal life. ~ 1 John 5:20

The deity of Jesus Christ is a major theme in the writings of John, who tells us that every spirit that denies the deity of Christ is not of God but is of the anti-Christ.

Those who confess the deity of Christ have the Spirit of God. This is consistent with Paul’s words to the Corinthians “no man can say Jesus is Lord, except by the Spirit of God”

True fellowship with God is fellowship with the one who John says is “eternal life” and who was with the Father from the beginning. Christ is Lord, and he is exalted, and by this truth (God manifest to us) we can know the difference between the Spirit of God and the  Spirit of error.

The Holy Spirit exaltes the Son of God.