Jesus told His disciples that if they wanted to be a part of His kingdom, it would be necessary for them to have a greater righteousness than the Pharisees and religious leaders had. There is only one righteous person who has ever lived that had that kind of righteousness, and it was Jesus Christ. The Good News of the Gospel is that “God made him who had no sin to be sin for us, so that in him we might become the righteousness of God” (2 Corinthians 5:21). He identified with us by taking on our humanity so that we could identify with Him and take on His righteousness.
We are made righteous by what Jesus did at Calvary. “For this reason he had to be made like them, fully human in every way, in order that he might become a merciful and faithful high priest in service to God, and that he might make atonement for the sins of the people.” (Hebrews 2:17) It is His atonement that makes us righteous and nothing else.
God is both inclusive and exclusive. He is inclusive in that whosoever may come to the Father, no matter what a person’s background is, the color of their skin, their nationality, whether they’re rich or poor, or any other characteristic. It doesn’t even matter how sinful they have been because God’s grace is always greater. But He is exclusive in this way: the only way people come to faith in Him is through the cross of Jesus Christ. Paul said, “I am not ashamed of the gospel because it is the power of God that brings salvation to everyone who believes: first to the Jew, then to the Gentile.” (Romans 1:16)