—2 John 7-8 (NASB)
To be absolutely sure, there IS a single individual that will rise to world prominence that holds the title of "antichrist"; but there is also a ROLE of the spirit of the antichrist that is played out by the evil one through his false prophets and false teachers amongst every generation of Believer. If we only focus on the one, End Times personality called "antichrist", we may fail to see the even more dangerous work that is going on ALL the time that is the spirit of the antichrist.
Why is it so important for us to believe, grasp, know for sure that Jesus came in the flesh? Among other things, if He came in some other form or as a supernatural being, then He really didn't live under the same rules as mankind, providing the ultimate example to which we can actually aspire. If He didn't come in the flesh, He wasn't the actual and physical sacrifice that was needed to atone for our sins. If He was not flesh and blood, many of His own statements and teachings would indict and convict Him as a fraud. It may sound like a "little" change, just a "small" alteration to interpretation of biblical information, but it leads to a complete and utter deception of something totally false.
Total deception is the evil one's primary goal, but John reveals a secondary goal if total deception cannot be effected: Less than a full reward. If such attacks on the truth are allowed to take even a minor hold, even though they may not ultimately result in causing us to fall completely away, they may destroy much of the work of the kingdom we've already accomplished. There will be casualties and consequences, even at the smallest tolerance of false teaching.
If you're one of those obsessed with whether the antichrist is born yet, who he might be, and when he'll appear, please strongly consider that you may be missing the point that his work is already present. If you don't watch yourself, you may "lose what we have accomplished".†††