If someone refuses to accept that Jesus came "in the flesh" he is rejecting the Word of God.

The antichrist spirit that denies that Christ came in the flesh two thousand years ago is the same spirit of unbelief that denies that Christ will literally come again in the flesh.

John also said that "every spirit that doesn't confess that Jesus Christ has come in the flesh is not of God.
And this is the spirit of the Antichrist, which you have heard was coming, and is now already in the world"  1 John 4:3.

This confirms the other Scriptures that tell us that the Spirit of God reveals the truth to us as He did to Peter.

John describes the nature of the spirit of Antichrist, "Who is a liar but he who denies that Jesus is the Christ? He is the antichrist who denies the Father and the Son."  1 John 2:22

The Bible says that anyone who denies that Jesus is the Messiah is denying the Father and the Son and has adopted the spirit of the antichrist.

The Antichrist is a liar because his father is Satan, the "father of lies" John 8:44.

His whole career from start to finish will be all deceit and lies.

People will accept his lies because they love darkness rather than light.

Jesus continually warned of the false messiah of the last days.

The False Prophet will present himself as the Prophet Elijah and try to counterfeit his miracle of bringing fire down from heaven.

The False Prophet must be a Jew to imitate Elijah.