To the church of God in Corinth, to those sanctified in Christ Jesus and called to be his holy people, together with all those everywhere who call on the name of our Lord Jesus Christ– their Lord and ours:
He will also keep you firm to the end, so that you will be blameless on the day of our Lord Jesus Christ.
1 Corinthians 1:2, 8 NIV
These two verses at the opening of the book of 1 Corinthians are very instructive. Between them they contain almost the entire understanding of holiness coming from the Old Testament into the New.
In the first place Paul says the Corinthians are holy (sanctified). The Corinthians? These divided people, boasting about their superior wisdom, harboring sexual perversion, looking down on the poor? These people are holy? Yes, they are, in the same sense that a bowl given to the temple is now holy. That is, it now belongs to God and should no longer be used for any purpose but his purposes. So Paul sees the Corinthians. Through Jesus they now belong to God.
But then he says that they are called to be (or become) holy. What does that mean? It means that Paul now expects them to bring their position into a state of reality. They are to dedicate themselves to actually becoming what their wonderful position implies: complete devotion to the Lord’s purposes and character. In some ways that is what the rest of the letter is calling for.
But is total dedication on the human side enough to receive that result? It is not. It is as God, responding to our dedication, fills us with his Spirit and makes our divided hearts (Jas 1:6-8) one for him (firm) that we become truly blameless (the outcome of holiness) before him. That term is not referring to some perfect performance. But it is referring to a spirit, an attitude, and a will that is completely his. This is holiness, Biblically speaking: position, consecration, Divine enablement.