1 John 4:3

3 and every spirit which does not confess Jesus Christ come in flesh is not of God: and this is that [power] of the antichrist, [of] which ye have heard that it comes, and now it is already in the world.

1 John 4:3 In-Context

1 Beloved, believe not every spirit, but prove the spirits, if they are of God; because many false prophets are gone out into the world.
2 Hereby ye know the Spirit of God: every spirit which confesses Jesus Christ come in flesh is of God;
3 and every spirit which does not confess Jesus Christ come in flesh is not of God: and this is that [power] of the antichrist, [of] which ye have heard that it comes, and now it is already in the world.
4 *Ye* are of God, children, and have overcome them, because greater is he that [is] in you than he that [is] in the world.
5 *They* are of the world; for this reason they speak [as] of the world, and the world hears them.
The Darby Translation is in the public domain.