* 1 John 2:18-19 - First, he is an individual who was prophesied to come in the end times. He, and those like him, will have been a part of the Church, but will break fellowship from us.
* 1 John 2:22-23 - Not only will he, and those like him, leave the fellowship of the Church, but they will deny that Jesus was Israel's Messiah. In addition, they will deny there is a Father/Son relationship between Almighty God and Jesus.
* 1 John 4:2-3 - The individual known as the Antichrist, will deny the Incarnation: that Jesus was God come in the flesh.
* 2 John 1:7 - Again, John emphasizes that all those who deny the Incarnation of Jesus, have the spirit of Antichrist.
However, the Beast of Revelation 13:1-10 appears to offer himself "in place of" Israel's Messiah. In order for Israel to be fooled into believing he is their Messiah, he will have to be a Jew, the son of David. Jesus taught His disciples that there would come a time when a false Christ would come and deceive many. Matthew 24:4-5 and 23-24 mentions those who will come pretending to be the Him. In Revelation 6:1-2, the "false Christ" comes riding on a white horse, just as Jesus will do when He returns (Rev. 19:11). He comes peaceably to Israel, and does not reveal himself to them until half way through the seven year covenant he confirms with them (Dan. 9:27; Mt. 24:5-28; Rev. 6 - 11).
I believe, while the two individuals definitely have the spirit of Antichrist, one is an apostate from the Church, and the other pretends to be Israel's Messiah. I suppose both identities could be of a single man, if he began by pretending he was a Christian, and then revealing he had been a Jew, of the lineage of David, all along. But that doesn't seem very likely.
The one thing both have in common is they are of their father, Satan, father of lies!