How do we know that the sacrifice of Christ is sufficient?

The sufficiency of Christ's sacrifice rests on His unique standing as the sinless High Priest who offered Himself once for all. Unlike the Old Testament priests who had to continually offer sacrifices that could never remove sins, Christ provided a definitive atonement through His own blood. Hebrews 10:14 asserts that by one offering, He has perfected forever those who are sanctified. This means that for those who trust in Him, their sins are completely dealt with, and they are deemed perfect in God's sight based on Christ's righteousness, not their own flawed attempts at holiness.