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

The book of Hebrews articulates the complete sufficiency of Christ's sacrifice through its teachings on the old and new covenants. Under the old covenant, sacrificial offerings were made repeatedly, showing their insufficiency for true atonement. However, Jesus Christ, as the perfect and eternal High Priest, offered Himself once for all, completing the work of redemption. Hebrews 10:14 explicitly states that by His one offering, He has perfected forever those who are sanctified, illustrating the finality and efficacy of His sacrifice, which negates the need for further offerings, as expressed in Hebrews 10:18.