Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world. (1 John 4:1)
We must be steadfast and know the Word and not let ourselves be blown about by winds of doctrine, the great swelling words of liars, false prophets, false pastors, even antichrists, and the final antichrist.
The end time Antichrist, the man of lawlessness is coming to deceive mankind and set up his own kingdom. This is akin to the devil thinking he won again. However, the Antichrist will be allowed for a season; that season will be called the Great Tribulation. But just as the devil thought he had defeated Jesus on the Cross, he was and will ultimately be sorely disappointed. The spirit of error is essential in paving the way for the final Antichrist.