Given the context of John's community, using the antichrist language is difficult to translate into modern times. Seems far to often we want to demonize public figures and ideas (presidents, chiefs of state, world leaders, politicians, athletes, video games, card games, etc.) as the antichrist.
The thing about naming everything evil is that nothing is evil and we miss out on what the devil is actually doing in the midst of us. Understanding that their is truly only one adversary (Satan) helps us identify what the little antichrists are doing. Since Satan's main message is to distract the faithful from fellowship with God, than anything that contributes to that could be identified as antichrists. HOWEVER, over naming something or someone can get to the misuse of such a powerful identification.
Therefore, John encourages his community to remains steadfast in the teaching from the Holy Spirit (That Jesus is Lord, divine and human), remain in fellowship and community under the name of Jesus (the church), be full of courage in this teaching so that you (we) cannot be led astray by the things of this world and all of the antichrists working on behalf of the greatest liar, Satan.
Lord, keep us steadfast in our faith by the power of your Holy Spirit encourage us to stand firm in our communties of faithful witness.- Amen