This is kind of old, and it doesn't explicitly say it, but I just so happened to have this laying around. The first paragraph suggests that all apostates, or anyone who is not inside the congregation, makes up the antichrist.
*** w86 7/15 pp. 13-14 Keep Walking in Divine Light ***
Guard Against Apostasy
20 John now warns against antichrists. (Read 1 John 2:18, 19.) He reminds fellow believers that from the apostles they “heard that antichrist is coming.” The appearance of “many antichrists” proved that it was the “last hour,” the final part of the apostolic period. Although those ‘against Christ’ formed a composite “antichrist,” many individual antichrists pretended to worship God but “were not of our sort” and abandoned true Christianity. We are glad that the departure or expulsion of such ones today prevents corruption of the congregation.
21 Apostate views are rejected by loyal spirit-begotten Christians. Since “an anointing from the holy one,” Jehovah, helps them to understand his Word, ‘all of them have knowledge.’ (Read 1 John 2:20, 21.) They surely know “the truth” as it relates to Jesus Christ, whereas the apostates have erroneous ideas about him. Since “no lie originates with the truth,” all lovers of Jehovah reject such false views and those advocating them.
22 After all, “who is the liar if it is not the one that denies that Jesus is the Christ,” God’s Anointed One? (Read 1 John 2:22-25.) Why, ‘the one that denies the Father and the Son is the antichrist’! Interestingly, when an early associate of Bible student Charles T. Russell denied the ransom, Russell withdrew from fellowship with him and began publishing this journal, which has always declared the truth about Christ’s origin, Messianic role, and loving service as the “propitiatory sacrifice.”
23 Apostates who deny Christ do not have Jehovah as their Friend. (John 5:23) But we who publicly ‘confess the Son have the Father,’ being in an approved relationship with God. (Matthew 10:32, 33) Jesus’ loyal early followers clung to what they had heard about God’s Son “from the beginning” of their lives as Christians. And if the same truth is in our hearts, we will “abide in union” with both God and Christ and will receive “the promised thing,” everlasting life.—John 17:3.