How do we know the sacrifice of Jesus is sufficient?

The sufficiency of Jesus' sacrifice is firmly established in Hebrews 10:14, which states that by one offering, He has perfected forever those who are sanctified. This means that through His death, Jesus fulfilled all that was required by the law, thereby satisfying God's justice completely. Unlike the repetitious sacrifices of the Old Testament, which were insufficient to take away sins, Christ's sacrifice was once for all, perfect and eternally effective. Believers can rest assured that their sanctification and perfection before God are entirely grounded in what Christ has accomplished, not in their own efforts or works.