How do we know that Christ's work was sufficient for salvation?

The sufficiency of Christ’s work for salvation is guaranteed by multiple scriptural affirmations, particularly His proclamation 'It is finished' in John 19:30. This moment marks the completion of His atoning work, revealing that all the necessary conditions for salvation have been met on behalf of God's elect. The Old Testament foreshadowed this fulfillment in the types and shadows of the sacrificial system, where Christ not only fulfilled the law but also bore the sins of His people as prophesied.

Additionally, verses like Hebrews 10:14 affirm that 'by one offering, He hath perfected forever them that are sanctified.' The fact that Jesus sat down at the right hand of God after offering His sacrifice indicates the finality and acceptance of His work. Believers can rest assured that their place in God's kingdom is secured through faith in this finished work, wholly apart from their own efforts or righteousness.