How do we know that Jesus' work on the cross was sufficient?

Jesus' declaration in John 19:30, 'It is finished,' encapsulates the fullness and sufficiency of His sacrificial work on the cross. This statement indicates that every requirement for atonement was fulfilled; there was nothing lacking in His sacrifice. The completeness of Christ's work also underscores the historic Christian conviction that salvation is entirely dependent on His merit and not our own. Further reiteration of this sufficiency can be found in the New Testament, particularly in Hebrews 10:14, which states that by one sacrifice, He has made perfect forever those who are being sanctified. Thus, the assurance of sufficiency is rooted in the totality of Jesus' actions as laid out in Scripture.