Theophylact of Bulgaria
He continually speaks of one and the same thing. By the commandment of love he persuades them to unity, so that they will not pass over to the deceivers. These already walk through the world and deny the coming of the Lord in the flesh.
By speaking of walking according to the commandment given from the beginning, he shows that the opinion of the erring heretics is new. He persuades the faithful to hold fast to this original commandment and not be carried away by the deception of the heretics.
For Christ also commanded His disciples concerning deceivers: "Many will come in My name, saying, 'I am He'; do not go after them" (Lk 21:8). Therefore he commands all who keep the commandments not to be deceived, but to regard as antichrist anyone who says this.
Read more (202 words)
In the Greek text it says: those who do not confess Jesus Christ as coming (έρχόμενον), not as having come (έλθόντα), in the flesh. From this it is clear that there were some who denied the second coming of Christ.
The Lord Himself, when He says that many will come in His name, speaks not of His first coming, but of His second. Nevertheless, it is entirely true that those who deny the second coming do not acknowledge the first.
For if the Lord has already come in the flesh and promised to come again, then clearly one who denies the second coming also denies the first. Whoever believes that the Lord came will also receive His promise with faith. But whoever rejects the promise is not prevented from denying the first coming also.
For this reason, I think, the Apostle said "coming," not "having come," so that by one word he might include those who deny both comings of the Lord. Such a man is a deceiver and an antichrist.
For greater clarity, before this one must understand the words: whoever does not confess this. Then read: he is a deceiver and an antichrist. Without this addition the discourse is incomplete.