How do we know salvation is completed through Christ?

In the sermon, it is emphasized that at the moment of His death, Christ declared, 'It is finished' (John 19:30). This statement confirms that His sacrificial work was complete, fulfilling all the requirements of God's law and satisfying divine justice. The prophets foretold that the Messiah would come to deal with sin directly, and through His death, Jesus secured eternal redemption, making it clear that no further sacrifice is needed. Hebrews 10 elaborates on this by explaining that Christ's single offering has perfected those who are being sanctified, reinforcing the belief that salvation is a finished work achieved by Christ alone, not dependent on human effort.