How do we know that Christ's redemptive work covers all believers?

The assurance that Christ's redemptive work covers all believers is found in Scripture passages such as John 6:38-39, where Jesus declares that He will lose none of those given to Him by the Father. Additionally, Matthew 1:21 affirms that Jesus came to save His people from their sins, indicating that His sacrifice was specific and effective for those whom the Father chose. This aligns with the doctrine of particular redemption within Reformed theology, which states that Christ's atonement is sufficient for all but efficient only for the elect. The consistency of these biblical teachings reinforces the belief that all whom Christ died for are fully redeemed and secure in His grace.