Therefore, if anyone cleanses himself from what is dishonorable, he will be a vessel for honorable use, set apart as holy, useful to the master of the house, ready for every good work. 2 Tim 2:21
Salvation is by grace through faith in Jesus Christ.
In other words, we did nothing to earn it, and we can do nothing to deserve it. It is only by the grace of God, that we are able to come into communion with Him. However, the fulfillment of our salvation marks the commencement of our sanctification.
Salvation is the completed work of God's grace. When Jesus declared from the cross, "it is finished," (John 19:30) He meant it. Salvation was purchased once and for all by the blood of Christ.
Sanctification is the progressive inflow of God's grace within us. God has done the heavy lifting. He has done what we could never do. And the only proper response to this salvation is to bear our cross daily and follow Him. If we do not actively bear our cross (in whatever way that may look for each of us) there is no reason to believe that we have truly accepted God's gift to us. It is through this process of dying to self - of crucifying the flesh - that we enable God's grace to find a home inside of us. The Holy Spirit lives inside of all believers, but the magnitude of His presence is directly proportional to the surface area we give Him.
Sanctification is the evidence of salvation. No one can truly come into contact with the glory of God and not be changed. No one has room to doubt their salvation when they are busy experiencing God's sanctifying work within themselves. Not until God cleans us of something we know we could not have accomplished under our own power do we know that the Holy Spirit lives within us.
Too often in modern American Christianity do we throw around the phrase "I'm saved," as an excuse for living a consciously sinful or lukewarm lifestyle. We spit in the face of a bloody Jesus hung on the cross every time we accept His gift of salvation and refuse to cooperate with His process of sanctification. The purification of our souls is not a burden, it is a gift from God. And it is not a matter that requires "figuring out" or "working harder." It is a matter that simply requires surrendering to the One who loves us more than we love ourselves. And it is a process that does not end until we leave this earth.
Jesus did not sacrifice Himself so that we could go to Heaven. He sacrificed Himself so that we could intimately walk with Him every day of our lives. Whether or not we want to take this walk is our choice, and our choice alone. Not even God can force our hand.
Since we have these promises, beloved,
let us cleanse ourselves from every defilement
of body and spirit,
bringing holiness to completion
in the fear of God
- 2 Cor 7:1