How do we know that Jesus's death was sufficient for salvation?

The sufficiency of Christ's death for salvation is foundational to Reformed theology, as it teaches that His sacrifice completely pays the penalty for the sins of those He came to save. The Apostle Paul articulates this in 2 Corinthians 5:21, noting that 'He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him.' This assures believers that Christ's work is fully effective, as there is no place for ambiguity in His capacity to save. Furthermore, Hebrews 10:14 states, 'For by one offering He has perfected forever those who are being sanctified,' demonstrating that His atonement was not temporary or partial but is eternally effective. This doctrine gives believers immense confidence, knowing that their salvation rests entirely upon what Christ has done.