How is sanctification described in Scripture?

Jason Dohm explains in this video that Peter gives a good description of sanctification in 2nd Peter. Sanctification begins inwardly and works its way outward - “Growing in the grace and knowledge of our Lord Jesus Christ.” Fundamentally then, we see that sanctification is growth, a growth in the knowledge of Christ.

Sanctification does involve certain external changes. These are defined in Scripture, by the commandments of God in both the Old and New Testament. When we do things that God prohibits in Scripture, we are kept from the better things. In contrast, the things that we are commanded to do are acts of love. The laws of God do tell us what the externals should look like, but we shouldn't attempt to mechanically follow them. Rather, they ought to stem from a love for God and His ways.

2 Peter 3:17-18 (NKJV) – “You therefore, beloved, since you know this beforehand, beware lest you also fall from your own steadfastness, being led away with the error of the wicked; but grow in the grace and knowledge of our Lord and Savior Jesus Christ. To Him be the glory both now and forever. Amen.”

So at the very end of his second letter, 2 Peter, Peter gives what I think is a great definition of sanctification. He doesn't use the word sanctification, but I think he describes it. Here's how he ends that letter in 2 Peter 3, verse 18. He says, but grow in the grace and knowledge of our Lord and Savior, Jesus Christ." So, this is what sanctification looks like. Now, that works its way outward.

This is internal sanctification. Growing in the grace and the knowledge of our Lord Jesus Christ. That means certain things externally, but it's not fundamentally external. Fundamentally, it is growth in the grace of Jesus, growing in his grace. It's growing in the knowledge of Jesus.

The externals are defined in Scripture, and It's defined by the commandments of God, Old Testament, and New. It tells us what we shouldn't be doing, what we should abstain from. Those things are never designed to keep us from good. They keep us from good. When we're doing things that God prohibits, we're actually kept from the better things.

That's the nature. The laws of God are laws of love. The New Testament is so clear about that. So we're not being kept from good things. On the other side, the things that we are commanded to do are acts of love.

They're, again, laws of love. And so the laws of God do tell us what the external should look like. But this isn't mere mechanical, sterile, cold, hard duty. Right, these are laws of love. They keep us from the love killers and promote the things that are loving to God and man.