Why is Jesus called the Mediator of the New Covenant?

Hebrews 9:15 emphasizes that Jesus serves as the Mediator of the New Covenant, illustrating His unique role in sealing the covenant through His death. The term 'mediator' denotes someone who acts as a go-between, ensuring that God's promises are fulfilled for His people. By His sacrificial death, Jesus redeems those under the former covenant and guarantees their inheritance—eternal life with God. His role as mediator reflects a profound covenantal relationship, whereby the triune God orchestrates salvation for His elect through the life, death, and resurrection of Christ.