The following is from a brief series of posts I did on Facebook. Forgive me if it seems slightly spliced together, but I would be interested in more discussion around this topic.
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Contrary to popular dogma otherwise, sanctification is not a progressive work, rather it's a definitive and completed work. God "set us apart" (sanctified) at conversion, just as He "sanctified" the seventh day at the creation of the world. (See 1 Cor. 6:11)
I believe instead of growing in "sanctification," we rather grow in "glorification." We look at things too negatively. We look at our growing process as sinning less and less. But you never see such a definition given in all of Scripture. Instead, you read about abounding in the fruit of the Spirit. Our growth is about becoming more Christ in the bearing of fruit, not in sinning less and less. Though we sin from time to time, progress in the Christian faith is defined as going "from faith to faith and glory to glory." Truth be told, we are not supposed to be sinning anyway. So, sinning less frequent is not exactly a positive measure of growth. Growing in knowledge, faith, love, patience, etc, this is how we measure growth.
We do have to daily kill the flesh and strive against sin. But that process is known Scripturally as "mortification." Many wrongly use the term "sanctification" instead.
Sanctification is the event whereby Jesus Christ set us apart, made us holy, and has caused us to sit in heavenly places with Him, and gave us the Holy Spirit. This all happened at the new birth, which has caused us to be "set apart" from the rest of the world as one's who have been spiritually made alive at the present moment.
Mortification is whereby we kill our flesh and crucify it everyday. Think of it as "sanctification applied." We take what Jesus already did for us, and we apply it continually throughout the entirity of our lives every day, as we wrestle against sinful desires of the flesh.
I think it is important for us to get these concepts and words right though. Otherwise, unless we see ourselves as anything less than fully sanctified from the moment we are born again, finding victory over sin in our mortification experience can be all the more difficult, as we think somehow Christ did not supply us with everything necessary to living the life He would have us to life, so as to bear fruit for the kigndom, and be the witnesses He has called us to be.
