How do we know the doctrine of tribulation is true?

The doctrine of tribulation is grounded in both the teachings of Christ and the apostolic letters. In John 16:33, Jesus declares, 'In the world ye shall have tribulation,' emphasizing that tribulation is part of the Christian journey. The apostle Paul corroborates this in Acts 14:22, stating that we must 'through much tribulation enter into the kingdom of God.' The experience of the early church and the prophetic writings in the New Testament highlight that tribulation is not a sign of God's absence but is a testimony of His work and promises amidst difficulties, assuring believers of their ultimate victory.