I haven't taken time to read the other responses.
I do not subscribe to sanctification being "progressive" anymore than I think "work out your own salvation" means that one has to work to be saved.
The word means (both noun sanctification and verb sanctify) basically "to set apart" or "having been set apart."
Unfortunately, some folks get the idea that the positional transfer involves one literally being taken from one position or state and repositioned to another state. For instance, one might move a lamp into a better place to give its light.
However, the Scriptures NEVER indicates such a movement takes place. Rather, the word is always in terms of the sanctification being completed and in a static position.
Look at this passage as an example from Scriptures from 1 Thessalonians 4:
4 Finally then, brethren, we request and exhort you in the Lord Jesus, that as you received from us instruction as to how you ought to walk and please God (just as you actually do walk), that you excel still more. 2 For you know what commandments we gave you by the authority of the Lord Jesus. 3 For this is the will of God, your sanctification; that is, that you abstain from sexual immorality; 4 that each of you know how to possess his own vessel in sanctification and honor, 5 not in lustful passion, like the Gentiles who do not know God; 6 and that no man transgress and defraud his brother in the matter because the Lord is the avenger in all these things, just as we also told you before and solemnly warned you. 7 For God has not called us for the purpose of impurity, but in sanctification. 8 So, he who rejects this is not rejecting man but the God who gives His Holy Spirit to you.
See how there is no movement taken by the believer to become more sanctified? There is no progress from one level of sanctification to another sanctification.
Rather, in each place (underlined) the sanctification is taken as complete and the believer should grow by what that sanctification brings.
Pictures of sanctification may go along these along these lines:
One purchases a car - the car is retitled from the dealer to the new owner. The car doesn't move, the title is transferred - just as a believer is "retitled" (set apart) from the authority of darkness into a child of light.
The local assembly decides to adjust the budget of expenditures designating a specific portion for certain use. All the money remains in a single account, but is designated for different purpose and to be used for another purpose than originally designated. Same with the unbeliever being "designated" (set apart) to the purpose of God.
Consider the tabernacle and all the elements that apply to the tabernacle; the "sanctifying" of the various parts of the tabernacle.
Did the parts hop about gaining more and more "sanctification?" Were they not pronounced holy by various methods of anointing? What of the priestly robes? Did Aaron polish the various parts of the high priestly robes to make them more "sanctified" or were they already sanctified and he had to wash and be cleaned before the robes were put on?
Look carefully at the use of the word in this passage from 1 Corinthians 6:
9 Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived; neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor homosexuals, 10 nor thieves, nor the covetous, nor drunkards, nor revilers, nor swindlers, will inherit the kingdom of God. 11 Such were some of you; but you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus Christ and in the Spirit of our God.
See how washing, sanctification, and justification are all accomplished for the believer? There is no more need of Christ being crucified again for the believer, no more need of re-sanctification, no further justification.
First there is the washing (remember Aaron had to wash), then the sanctification (remember the robes were put on), then the justification (Aaron could go about the work of the priest).
If one takes sanctification as "progressive" it is a violation of these two passages of Scriptures and the picture of what great accomplishment God has done in the work of redemption in which sanctification is one part.
There are many who would disagree and place the believer's growth and move toward being more Christlike as sanctification, but each of those verses such as "be holy as I am holy" are not sanctification verses, but the impulses from God through sanctification that press the believer to greater likeness of Christ.
