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

The sufficiency of Christ's sacrifice is central to the doctrine of atonement in Reformed theology. Hebrews 10:10 confirms that we are sanctified through the offering of the body of Jesus Christ once for all. Unlike the Old Testament sacrifices, which were merely types and shadows, the death of Christ completely fulfilled the requirements of the law and secured eternal redemption. When Jesus declared 'It is finished' (John 19:30), He affirmed that the full price for sin had been paid. The resurrection further endorses the sufficiency of His sacrifice, as it demonstrates God’s acceptance of Christ’s work on our behalf. The certainty of salvation is directly tied to the completed work of Christ on the cross, assuring us that it is His righteousness, not our own efforts, that makes us acceptable to God.