How do we know that Jesus' sacrifice is sufficient for salvation?

Hebrews 10:12 states that Christ, after offering one sacrifice for sins forever, sat down at the right hand of God, indicating that His sacrifice was complete and sufficient for all sin. Unlike the repetitive sacrifices of the Old Testament, which could never take away sins, Christ’s single offering perfected forever those who are sanctified. This truth is foundational in Reformed theology, emphasizing that salvation is fully secured through Christ’s atonement, eliminating the need for any further sacrifices.