How do we know the doctrine of Christ as our High Priest is true?

Hebrews explicitly identifies Jesus Christ as our High Priest, a role He fulfills uniquely compared to the old priesthood established under Moses and Aaron. Unlike other priests, who offered sacrifices for their own sins and the sins of the people, Jesus is without sin and offered Himself as the perfect sacrifice. His intercession for His people is both effective and ongoing, as He does not pray for everyone, but for those the Father has given to Him (John 17:9). This understanding underscores the assurance and confidence believers can have in His ability to mediate on their behalf before God.