The biggest heresy that started with the Catholic (in the year 325, with the Council of Nicaea, and after with Ephesus, in 431, was to start the Trinity, this great heresy against Christ), and they all adopted. There are many texts that contradict this abomination, which makes God into a man and the man a god; John in this text continues to alert us of the liars and the fake, the sons of the devil, the father of the lie. 1° John 2:
John: 2- 22- Who is a liar but he that denieth that Jesus is the Christ? He is antichrist, that denieth the Father and the Son.
23- Whosoever denieth the Son, the same hath not the Father: [(but) he that acknowledgeth the Son hath the Father also].
26- These [things] have I written unto you concerning them that seduce you.
John alerts us that there are two spirits acting in the world: the spirit of God and the spirit of the antichrist. 1º John 4:
1- Beloved, believe not every spirit, but

try the spirits whether they are of God: because many false prophets are gone out into the world.
3- 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.
John speaks that the antichrist, acts spiritually preparing his arrival long ago but, at this moment, He already is physically in the world, waiting for the moment to manifest and lead the many antichrists (fake Christians), that behold his spirit of error. 1º John 4:
6- We are of God: he that knoweth God heareth us; he that is not of God heareth not us. Hereby know we the spirit of truth, and the spirit of error.
In: 2º John 7 to 11. He speaks again that many of the deceivers have gone throughout the world; they don’t accept the Christ that came in flesh, and go beyond the word.