Why is assurance in Christ important for Christians?

The assurance of salvation is vital for Christians as it is rooted in the completed work of Christ. Hebrews 10:14 states that through one offering, He hath perfected forever them that are sanctified. This assurance allows believers to stand before God without fear of condemnation since they are justified in Christ. Instead of relying on their own performances, which can lead to despair due to sin, believers can trust in the unchanging nature of Christ's righteousness, which is imputed to them. This provides both comfort and confidence in their eternal standing before God.