Of course it is. You aren't suggesting that the 3 books contradict each other, are you?
The anti-Christ isn't a concept. It is a real thing.
I agree with you on that. Those scriptures don't contradict eachother. Revelation doesn't contradict 1 and 2 John because it never mentions "Antichrist" being one person. It never mentions the word Antichrist at all. These are the scriptures that explicitly mention "Antichrist":
1 John 2:18: Children, it is the last hour, and just as you heard that the antichrist is coming, so now many antichrists have appeared. We know from this that it is the last hour.
1 John 2:22: Who is the liar but the person who denies that Jesus is the Christ? This one is the antichrist: the person who denies the Father and the Son.
1 John 4:3: but every spirit that does not confess Jesus is not from God, and this is the spirit of the antichrist, which you have heard is coming, and now is already in the world.
2 John 1:7: For many deceivers have gone out into the world, people who do not confess Jesus as Christ coming in the flesh. This person is the deceiver and the antichrist!
So what do you make of 1 John 2:18 where it says "many antichrists" for instance?