How do we know that Jesus Christ is the final spokesman for God?

Hebrews 1 establishes that God has spoken at various times through prophets, but in these last days, He has spoken to us through His Son, Jesus Christ. Jesus Christ is described as the brightness of God's glory and the express image of His person, illustrating His divine authority. This final revelation through Christ is underscored by the fact that He fulfilled the law and brought the message of salvation, making Him superior to angels and prophets alike. His resurrection and the fulfillment of Old Testament prophecies further confirm His role as the ultimate spokesman.