It seems you're having trouble with the concept of committing sin, but not being a sinner.
A sinner is someone who transgresses against divine law. It is in their nature to sin. "Sinner" describes their nature, it's who they are. Can they do something righteous? Of course. That doesn't change their nature of being a sinner, though.
A saint is someone who has been acknowledged as holy or virtuous or righteous. It is not in their nature to sin. "Saint" or "saved" describes their nature, it's who they are. Can they sin? Of course they can, but that doesn't change their nature from saint to sinner, it just means that they did something against their nature.
This is what Paul was saying in Galatians 2:17, that if he, and every Christian for that matter, is still a sinner (talking about their nature), then Christ is a minister of sin. Of course, Christ is not a minister of sin, He's a minister of righteousness.
“But if, while we seek to be justified by Christ, we ourselves also are found sinners, is Christ therefore a minister of sin? Certainly not! - Galatians 2:17 http://www.biblegateway.com/passage/?search=Galatians2:17&version=NKJV
Therefore, we are no longer sinners, but saints, saved eternally, and nothing can take that away from us.
But God demonstrates His own love toward us, in that while we were still sinners, Christ died for us.Much more then, having now been justified by His blood, we shall be saved from wrath through Him.For if when we were enemies we were reconciled to God through the death of His Son, much more, having been reconciled, we shall be saved by His life.And not only that, but we also rejoice in God through our Lord Jesus Christ, through whom we have now received the reconciliation. - Romans 5:8-11 http://www.biblegateway.com/passage/?search=Romans5:8-11&version=NKJV
What then shall we say to these things? If God is for us, who can be against us?He who did not spare His own Son, but delivered Him up for us all, how shall He not with Him also freely give us all things?Who shall bring a charge against God’s elect? It is God who justifies.Who is he who condemns? It is Christ who died, and furthermore is also risen, who is even at the right hand of God, who also makes intercession for us.Who shall separate us from the love of Christ? Shall tribulation, or distress, or persecution, or famine, or nakedness, or peril, or sword?As it is written: “For Your sake we are killed all day long; We are accounted as sheep for the slaughter.”Yet in all these things we are more than conquerors through Him who loved us.For I am persuaded that neither death nor life, nor angels nor principalities nor powers, nor things present nor things to come,nor height nor depth, nor any other created thing, shall be able to separate us from the love of God which is in Christ Jesus our Lord. - Romans 8:31-39 http://www.biblegateway.com/passage/?search=Romans8:31-39&version=NKJV
For we do not want you to be ignorant, brethren, of our trouble which came to us in Asia: that we were burdened beyond measure, above strength, so that we despaired even of life.Yes, we had the sentence of death in ourselves, that we should not trust in ourselves but in God who raises the dead,who delivered us from so great a death, and does deliver us; in whom we trust that He will still deliver us,you also helping together in prayer for us, that thanks may be given by many persons on our behalf for the gift granted to us through many. - 2 Corinthians 1:8-11 http://www.biblegateway.com/passage/?search=2Corinthians1:8-11&version=NKJV
Remember, our salvation is in Christ, not in our works. There is nothing we can do that is greater than His love for us if we have accepted him into our lives. If there was, then Christ would have died for nothing, and there would be no hope at all for us.
