Albert Barnes Commentary 2 John 1:7

"For many deceivers are gone forth into the world, [even] they that confess not that Jesus Christ cometh in the flesh. This is the deceiver and the antichrist." — 2 John 1:7 (ASV)

For. oti. This word "for" is not here to be regarded as connected with the previous verse, and as giving a reason why there should be the exercise of mutual love. Instead, it is to be understood as connected with the following verse (2 John 1:8), and as giving a reason for the caution expressed there: "Because it is a truth that many deceivers have appeared, or since it has occurred that many such are abroad, look to yourselves lest you be betrayed and ruined." The fact that there were many such deceivers was a good reason for being constantly on their guard, lest they should be so far drawn away as not to receive a full reward.

Many deceivers are entered into the world. They are abroad in the world, or have appeared among men. Several manuscripts read here, "have gone out into the world," exhlyon, instead of "have entered into," eishlyon. The common reading is the correct one, and the other was originated, probably, from the unusual form of the expression, "have come into the world," as if they had come from another abode. That, however, is not necessarily implied, as the language would be properly used to denote the idea that there were such deceivers in the world.

Who confess not that Jesus Christ is come in the flesh. These are those who maintain that He assumed the appearance only of a man, and was not really incarnate. See Barnes' notes on 1 John 1:2 and 1 John 1:3.

This is a deceiver. Every one who maintains this is to be regarded as a deceiver. And an antichrist. See Barnes' notes on 1 John 2:18 and 1 John 4:3.