The flip side to this legalism is usually described as license. Which simply is a freedom to willfully pursue sin and all its perceived pleasures. Somehow assuming the grace of God makes way for sin rather than grace makes way to not sin. Living as a "Christian" with either of these worldviews will make for a slow miserable death. Thank God for Jesus! In Him we have all that we need for life and godliness (2 Peter 1:3-11). Our obedience is is one that learns not one that earns. We learn about God and ourselves not earn from God for ourselves. Amen!
Are these the only two options though? At times I get concerned that we, people in general, are primarily satisfied with placing "things" in one of two categories. We are in the "either or" worldview often in our description of life and the hereafter. Maybe because there really are two kinds of people in this world from the bible's perspective, reconciled and unreconciled. Maybe because there really are 2 ways to live. Although Tim Keller has recently been pushing that there are in fact 3 ways to live. All this being said, I believe there is at least one more, and in my opinion, one that is very infamous among Believers, when we get Justification and Sanctification confused. The problem is I don't have a good theological term for it like the two above. Right now I have packaged it as good ol' fashioned "Meology." A street way to say this is "a holy zap" or "Sudden Sanctification." This is a more common response than not for the believer when justification is viewed as a process.
Sudden Sanctification is when the believer confuses sanctification (on going/progressive process of becoming like Jesus) with justification (instantaneous act in which God declares the sinner as righteous, as if he never sinned at all) and believes that sanctification should be instantaneous. This is the evil twin of legalism which states, in essence, that justification is a process as opposed to an instance. What this looks like is the believer is shocked at their sin, discouraged at the rate of their growth and often bitter towards God and or others that seem to "get it" when it comes to doing the Jesus thing. Other symptoms include, nausea, diarrhea, loss of hair, one leg growing longer than the other and an intense search for Baked Beaver Back as an evening dish. The worst of it all is that the believer thinks that this desire to be holy quickly honors God and is humble and passionate but in actuality it is an expression of severe arrogance and complaint towards God who designs all processes for His people in order that they may grow to be like him, while being dependent on Him. There is no such thing as a holy zap! There never will be. While there are some areas that will radically come to a halt. Often many of the areas you and I struggle with will remain on some level as the thorn in our flesh to keep us humbly dependent on His righteousness to guide us into eternity.
"Sudden Sanctification" says to God, "I hate this sin and how it makes me feel and I want you to take it away, NOW!" This mindset forgets 1 Peter 4:12-19, James 1:2-4, 2 Peter 1:3-11, Hebrews 12:11, Galatians 6:7-9 and many other wonderful passages that highlight the reality of who God is and what He has done. As a pastor I often come across people who want the desires and effects of sin to go away and actually expect them to as quickly as they say it. I regret to inform you that there is no such thing. Sanctification is indeed a process. It is a process given only to those whom are called by God. It is a gift and it produces the kind of character that pleases God. We focus so much on the goal that we forget that God is focused on the process. He has already called us "not guilty," justified by the blood of Christ. The goal is already achieved. The process needs to be received.
Perseverance is the name of the game here. This glorifies God! I know in my life there are quite a few areas where I wish God would give me a holy zap. But my desire is selfish. It's not about honoring God it's about not wanting to do the work of long suffering with my sin and it also requires no faith. The work of the spirit is sufficient and will be complete. Let Justification be instantaneous and sanctification be contemporaneous. When we confuse the two the outcome is one of anguish and confusion. "For if you live according to the flesh you will die, but if by the Spirit you put to death the deeds of the body, you will live" (Romans 8:13)