How do we know the doctrine of the Antichrist is true?

The truth of the doctrine concerning the Antichrist is established through various scriptural references, particularly from the epistles of Paul and John. In 2 Thessalonians 2, Paul articulates the events that must precede Christ's return, notably the revelation of the man of sin. Likewise, 1 John warns that many antichrists have come, indicating a consistent biblical theme of opposition to Christ and his Gospel within the church. The historical manifestations of this spirit of antichrist can also be observed in the form of false doctrines and challenges to the Gospel, affirming the ongoing relevance of this doctrine in understanding spiritual deception.