How do we know the doctrine of the man of sin is true?

The doctrine of the man of sin, often associated with the Antichrist, is grounded in biblical prophecy, particularly in 2 Thessalonians 2:3-4, where Paul speaks of a figure who opposes God and sets himself up in God's temple. This truth is further explored by recognizing the historical context of the early church and the emergence of apostate Christianity. The character described aligns with various historical figures throughout church history that sought to usurp Christ's authority, especially within the context of the Papacy. Thus, the scriptures both warned of and revealed a future apostasy, which has progressively unfolded, reaffirming the validity of this doctrine.