How do we know that Christ's sacrifice was sufficient?

The sufficiency of Christ's sacrifice is anchored in its singular nature and its divine institution. Hebrews 9:26 states that Christ appeared to put away sin by the sacrifice of Himself, marking an end to the repetitive animal sacrifices mandated in the Old Testament. This unique offering demonstrates that He, as the perfect Lamb of God, fully met the justice required by God's holiness.

Furthermore, the efficacy of His sacrifice is evident in the result it achieved—those who believe are granted complete remission of sins and entrance into the presence of God. As the letter to the Hebrews underscores, Christ's blood enters the heavenly tabernacle, interceding for us, thus forever establishing a once-for-all atonement that is effective for all who are called by God. Therefore, the doctrine of Christ's sufficiency in atonement and salvation is central to Reformed theology, summing up our assurance in His finished work.