How do we know Christ is the mediator of the New Covenant?

Jesus Christ is affirmed as the mediator of the New Covenant through various biblical texts that highlight His unique role in salvation history. In Hebrews, the author declares that Christ has fulfilled the Old Testament prophecies and sacrificial systems, which were shadows pointing to His redemptive work. As the mediator, He perfectly fulfills the requirements of the law and represents His people before God, taking upon Himself their sins through His sacrificial death. This role is elaborated in Hebrews 10:12, which contrasts Christ's one perfect sacrifice to the repeated sacrifices of the Old Covenant, emphasizing that He has successfully completed the work necessary for the redemption of His people.