How do we know that Jesus saves sinful people?

The salvation of sinful people is rooted in the reality of substitutionary atonement, whereby Jesus, as the perfect Savior, took upon Himself the sins of those He came to save. He drank the bitter cup of God's wrath against sin, allowing believers to be united with Him in His death and resurrection. Through this union, as mentioned in Matthew 20:23, believers share in His suffering and are cleansed from their sins. Jesus' death was not only for the elect but a demonstration of God's grace in saving those who, in their sinful nature, are unworthy of such grace. This gives assurance to believers that their salvation is secure, not based on their merit but solely on Christ's obedience and sacrifice.