The small texts that mention the "antichrist" were written to attack the Gnostic understanding of who Christ was. A Gnostic relies on intuition and not on dogma and doctrine. Gnostic's were most certainly free spirits and most all of the writings we have about Gnostics, have been the attacks upon them. That all changed when the Nag Hamadi Library was translated and published, for what had been deemed heretical by those in power in the fourth century can now be read in most every language.
We may never know if the author who coined the term "antichrist" was actually the apostle John who wrote I John and 2 John-the only sources where the term appears.
John also say's much more:
...as you have heard that the antichrist is coming, even now many have come..."- I John 2:18
"If anyone has material possessions and see's his brother in need but has no pity on him, how can the love of God be in him? ...let us love with actions and in truth."-I John 3:17
"God is love. Whoever lives in love lives in God, and God in him. There is no fear in love. Perfect love drives out all fear because fear has to do with punishment."
The theology promoted in the "Left Behind" fiction is a theology based on fear and punishment. These misinformed Christian's worship a punitive father as God.
Many do not have eyes to see that nature is God's primary temple, and war the greatest abomination.
During the time when John was writing about the spirit of antichrist, Gnosticism was still in it's evolution and far from the intricately developed system of the second and third centuries when the church and it's institutional hierarchy became firmly established. During the time John was writing against the false teachings, the Gnostics were by and large libertines who denied Christ's humanity. Some said that Christ only appeared to have a body; others said the divine Christ joined the man Jesus at his baptism and left him when he died.
The Gnostics left no testimony in their behalf, so all we have to go on is what was written against them and the texts that survived and are now the Nag Hamadi Library. These texts offer no new information but prove that early Christian's were just as diverse as Christians today.
The Armageddon groupies believe they will be lifted out of the misery of the world, and neglect to reflect upon the antichrist within, which is how centuries of theologians understood the term.
Jesus said: "Whoever blasphemes against the father will be forgiven, whoever blasphemes against the son will be forgiven, but whoever blasphemes against the Holy Spirit will not be forgiven either on earth or in heaven."
The Holy Spirit, AKA the spirit of God is within all created things.