How do we know John the Baptist believed Jesus was the Messiah?

Despite being imprisoned and facing imminent death, John the Baptist's faith in Jesus as the Messiah remained steadfast. In Matthew 11:2-3, he sends his disciples to Jesus with a question about His identity, which some interpret as doubt. However, it's crucial to understand that John was not doubting; rather, he sought affirmation for his disciples to strengthen their faith. Jesus' response pointed to His miraculous works fulfilling Old Testament prophecies, confirming that John had accurately proclaimed Him as the promised Messiah. John’s unwavering faith and recognition of Jesus' authority showcase that he truly believed in the one he had heralded.