II Tim. 1:9 It is God who saved us and chose us to live a holy life. He did this not because we deserved it, but because that was his plan long before the world began--to show his love and kindness to us through Christ Jesus.
No one can save himself from God's wrath. No one can earn their way into God's favor. No one can live a holy life on their own. There is absolutely nothing we can do that is going to help us be a child of God. We are saved and made holy by what Christ does for us. Period.
Why would Jesus do what He has done for us? He loves us eternally and before He ever created anything, He made the decision to make it possible for us to be saved. God knew what it would take for us to be made holy before Him and committed himself to doing it. He knew before He created us that we would reject Him and spurn His love. He knew that sin would captivate our souls and condemn us to hell. He knew that only He could change our sinful hearts and make us holy. Because He created us in His own image to be the objects of His love and to have fellowship with Him, He made the decision to come to earth to die for our sins at Calvary.
There is no greater display of love than the love God showed us through the life, death, burial and resurrection of Jesus. Jesus is God's display of love for all humanity for all time. No one can love God and live for Him apart from Jesus. Calvary makes it possible for us to to saved and made holy before God. Jesus is the ONLY way we can have life in God for all of eternity.