Of course, the short answer is that the antichrist is the Jews, because the Jews deny that the Jewish Messiah has come in the flesh. However, the Jews are not who the author of the epistles of John is writing about. The author is writing about people who have left the Christian faith.
“Little children, it is the last time: and as ye have heard that antichrist shall come, even now are there many antichrists; whereby we know that it is the last time. They went out from us, but they were not of us; for if they had been of us, they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us.” (1 John 2:18-19).
Evidently the folks leaving the faith were calling the faithful a bunch of liars because the author says that what he is teaching “is no lie” (verse 27) but the real liar is the one who denies that Jesus is the Messiah (verse 22).
Now, why were these former believers denying that Jesus was the Messiah? Because, just as above, they had been taught that it was “the last time” and that Jesus would return in their generation.
They went out saying, “Where is the promise of his coming? for since the fathers fell asleep, all things continue as they were from the beginning of the creation.” (2 Pet. 3:4).
So, the dissenters had finally realized that the generation Jesus was talking about in Mark 13, Matt. 24 and Luke 21 was past, “since the fathers fell asleep”, and they were the next generation and the end still had not come and Jesus still had not returned. However, the author of the epistles of Peter still wanted them to believe that the time of the end was at hand.
“But the end of all things is at hand:” (1 Pet. 4:7).
The New Testament is full of passages that say that “the time is short” and it is “the last days” and the time is at hand etc.
What conclusion could those Christian dissenters have come to except that they had been deceived and Jesus was not the Messiah? Therefore, it was Christian dissenters who the author of the epistles of John is calling the antichrist and are the same ones who the author of 2 Peter calls “scoffers” and this also makes him declare that it was “the last days”, 2,000 years ago (2 Pet. 3:3).
No! Obama is not the antichrist.