We are sanctified by faith so that we might obey the Law.
Christ, by His righteousness, intercedes for us before the Father, so that we might be declared righteous, He being our advocate. In just the same way, by making us participants in His Spirit, He sanctifies us, in order to make us pure and innocent. For the Spirit of the Lord came upon Him without measure — the Spirit of wisdom, of understanding, of counsel, of strength, of knowledge, and of the fear of the Lord — in order that we might all draw from His fulness and receive grace from the grace given to Him (see John 1:16)
14 And the Word became flesh, and dwelt among us, and we saw His glory, glory as of the only begotten from the Father, full of grace and truth. 15 John *testified about Him and cried out, saying, “This was He of whom I said, ‘He who comes after me has a higher rank than I, for He existed before me.’” 16 For of His fullness we have all received, and grace upon grace. John 1:14-16
Those, then, who boast of their Christian faith while being at the same time entirely without the Spirit’s sanctification, deceive themselves. For the Scripture teaches that Christ has not only been made righteousness for us, but also sanctification. As a result, we cannot receive His righteousness by faith without embracing at the same time that sanctification. The Lord, by that covenant which He made with us in Christ, promises that He will both take away our sins and write His Law in our hearts (Jeremiah 31:31-34; Hebrews 8:6-12 and 10:11-18)
31 “Behold, days are coming,” declares the Lord, “when I will make a new covenant with the house of Israel and with the house of Judah, 32 not like the covenant which I made with their fathers in the day I took them by the hand to bring them out of the land of Egypt, My covenant which they broke, although I was a husband to them,” declares the Lord.33 “But this is the covenant which I will make with the house of Israel after those days,” declares the Lord, “I will put My law within them and on their heart I will write it; and I will be their God, and they shall be My people. 34 They will not teach again, each man his neighbor and each man his brother, saying, ‘Know the Lord,’ for they will all know Me, from the least of them to the greatest of them,” declares the Lord, “for I will forgive their iniquity, and their sin I will remember no more.” Jeremiah 31:31-34
6 But now He has obtained a more excellent ministry, by as much as He is also the mediator of a better covenant, which has been enacted on better promises.
7 For if that first covenant had been faultless, there would have been no occasion sought for a second. 8 For finding fault with them, He says,
“Behold, days are coming, says the Lord,
When I will effect a new covenant
With the house of Israel and with the house of Judah;
9 Not like the covenant which I made with their fathers
On the day when I took them by the hand
To lead them out of the land of Egypt;
For they did not continue in My covenant,
And I did not care for them, says the Lord.
10 “For this is the covenant that I will make with the house of Israel
After those days, says the Lord:
I will put My laws into their minds,
And I will write them on their hearts.
And I will be their God,
And they shall be My people.
11 “And they shall not teach everyone his fellow citizen,
And everyone his brother, saying, ‘Know the Lord,’
For all will know Me,
From the least to the greatest of them.
12 “For I will be merciful to their iniquities,
And I will remember their sins no more.” Hebrews 8:6-12
11 Every priest stands daily ministering and offering time after time the same sacrifices, which can never take away sins;12 but He, having offered one sacrifice for sins for all time, sat down at the right hand of God, 13 waiting from that time onward until His enemies be made a footstool for His feet. 14 For by one offering He has perfected for all time those who are sanctified. 15 And the Holy Spirit also testifies to us; for after saying,
16 “This is the covenant that I will make with them
After those days, says the Lord:
I will put My laws upon their heart,
And on their mind I will write them,”
He then says,
17 “And their sins and their lawless deeds
I will remember no more.”
18 Now where there is forgiveness of these things, there is no longer any offering for sin. Hebrews 10:11-18
Obedience to the Law is not, then, a work within our power to accomplish. The power to accomplish this work comes from the Spirit who cleanses our hearts from their corruption, and softens them to be obedient to righteousness.
Now the Law is of no use at all for Christians, outside of faith. In former days the outward teaching of the Law did nothing but accuse us of weakness and transgression. But since the Lord has engraved a love for His righteousness in our hearts, the Law is a guiding lamp to keep us from leaving the right road. It is the wisdom which trains us, instructs us and encourages us to become upright. It is our rule, and it will not tolerate being destroyed by wrongful liberty.
John Calvin, Truth For All Time, pp. 31, 32