If I asked you the question, "Why did Jesus die on the cross," what would you say to me? Probably, I'm guessing, that He died to save us. And I would affirm that. However, if I asked you what "save" means, what would you say to me? Most people would say something like, "Well, it means we go to heaven when we die." And I would say, "That's true, but only partially true."
You see, most people think of salvation in terms of what location they will be entering when they die; but that isn't the whole of it, nor is it the goal of it. The goal is not a physical destination, although we certainly want to be in the right place when we die, but the goal of God in salvation is to make us righteous, as righteous as Christ.
Now, we are clearly nothing like Christ when God justifies us through faith. It is while we are dead in sin, sinners (i.e., those who are in rebellion against God and not obedient to Him), that Christ died for us and God saved us. In declaring us righteous, He is declaring a status to us that could never have been gained by us, nor could it be. As Ephesians says, "He has raised us up and seated us in the heavenly places in Christ Jesus" (2:6). In other words, we have already positionally arrived at the destination of God's presence in Christ, in whom we now stand and who is our representative. Because we are in Christ, we are given all that Christ is given and considered to be righteous as Christ is righteous. Christ's salvation is a sure sign that we who are in Him are saved. We can think of it like a race, where we are all miles behind, except Christ who has crossed the finish line. All that was required for the team to win was that a single person, who represents the team, win. So He has won the race for us. Yet, the team now is still running toward the finish line, not to win the race, since that is already won, but simply to join their teammate in the victory he has now gained for them.
So what is the goal of God for those who have faith in Christ? It is for them to trust in Christ as the One who has won the race, but Christ has won the race so that they can now join Him across the finish line.
Now, you may be thinking that the finish line is heaven, and as I said before, that is partially true, but the finish line is really righteousness. Let's look at a couple verses:
Blessed [be] the God and Father of our Lord Jesus Christ, who has blessed us with every spiritual blessing in the heavenly [places] in Christ, just as He chose us in Him before the foundation of the world, that we would be holy and blameless before Him. (Eph 1:3-4)
Notice that what God chose us to be in Christ before the foundation of the world. Notice that this is the goal of God for us: to be holy and blameless. That is God's goal for His people. That is why He saved us. That is why Jesus died on the cross.
Again, Romans 8:28-30 is instructive:
And we know that God causes all things to work together for good to those who love God, to those who are called according to [His] purpose. For those whom He foreknew, He also predestined [to become] conformed to the image of His Son, so that He would be the firstborn among many brethren; and these whom He predestined, He also called; and these whom He called, He also justified; and these whom He justified, He also glorified.
Notice again that the goal is not just that we get to go to heaven when we die, but that God's purpose, for which He works all things, is to conform us to the image of His Son. This is why God takes us through this journey of salvation from predestining us, calling us in our hearing of the spoken gospel, justifying us (i.e., declaring us positionally righteous with Christ), and glorifying us (i.e., actually completing the righteousness of Christ in us).
In other words, Christianity isn't just about getting a bunch of people who couldn't care less about becoming holy to heaven. It's about calling sinners to repentance, so that they are declared righteous, have a place secured by Christ in God's presence, and begin their journey to become like Christ, holy and blameless. This is why staying a rebel toward God while claiming to be saved is nonsense. God gives His people His Spirit so that they are compelled onward toward Christ and His righteousness. He who does not have the Spirit who does so proves himself to not belong to Christ (Rom 8:9).
What I'm saying, then, is that God's purpose in giving you the gospel was never to just save you from going to hell, although that is a massive part of it. It was always meant to save you from the rebellious life that initially brought you there. His goal is to make you like Christ, to make you holy and blameless. He does this through justification, which declares you to be positionally righteous through Christ's gaining of that righteousness for you, and sanctification, which is the lifelong process of God conforming us to the image of His Son. No one, therefore, should justify his or her remaining in sin as a Christian because "nobody's perfect," or "we're all sinners anyway." We are all sinners, but if we have been justified, we should be moving toward holiness, not rebellion.
Hence, when it says that we are saved by grace through faith and that not of ourselves in Ephesians 2:8-10, we are told that the purpose of this is so that we would walk (i.e., live) in good works that God prepared beforehand for us. In Philippians 2:12-13, after Paul has just spoken about the work of Christ on the cross in saving us for the glory of God, we are told to "work out our salvation with fear and trembling, for it is God who is at work in you, both to will and to work for [His] good pleasure." Notice that this says, "work out," not "work for" salvation. We are working out the salvation, the righteousness, that has already been given to us in Christ. We are becoming what we have been declared and adopted to be already. That is the movement of the Christian, i.e., toward actualizing our holiness and blamelessness in Christ, so that we become like Him.
This is why we rebuke, correct, exhort, and encourage toward righteousness. It has nothing to do with being judgmental or legalistic. We do not confuse justification with sanctification, nor do we dare say that it is through the outward performance of the Law rather than faith in Christ by means of His Spirit through His Word by which we are sanctified. But neither do we say that salvation is merely a destination rather than a race that God has set us on to run. This is part of what theologians call the "already, not-yet." We have already won the race in being given the righteousness of Christ in terms of God's declaring it to be so and accepting us and our prayers in His presence on those terms, but we have not yet won it by becoming like Christ ourselves.
Hence, all who are justified are compelled down the road toward becoming sanctified in their daily lives. Those who are not compelled down that road will either be disciplined by God to start moving down it, or they are simply not His to begin with. But have no doubt, Christ saved us to be saved from a life of sin, not to be satisfied in our slavery to it. He has freed us from sin, not to live in it, but to live to God, moving ever closer to Christ and His righteousness in love. That's why Christ died, and we ought not trample on the cross in order to justify a life set against Him any longer. Seek, therefore, not only to be saved from hell, but from the road that leads there as well.
What shall we say then? Are we to continue in sin so that grace may increase? May it never be! How shall we who died to sin still live in it? Or do you not know that all of us who have been baptized into Christ Jesus have been baptized into His death? Therefore we have been buried with Him through baptism into death, so that as Christ was raised from the dead through the glory of the Father, so we too might walk in newness of life. For if we have become united with [Him] in the likeness of His death, certainly we shall also be [in the likeness] of His resurrection . . . (Rom 6:1-5)