In the Christian life, holiness is not optional. Many Christians seem to think about holiness as if it is like something added to a car, such as fancy leather upholstery instead of the normal kind of plastic. But that is not true.
Holiness is an essential part of salvation. In Hebrews 12:14 the writer says, Pursue peace with all people, and holiness, without which no man will see the Lord. What salvation do we have that does not bring us to see the Lord? But without holiness, no one will see the Lord.
We have in our contemporary Western Christianity a very incomplete picture of salvation. ‘If I get saved and born again, and then I want to go on and be holy. I can do it - but it is an option.’ I want to tell you that your salvation depends on your being holy. And holiness comes only from the Holy Spirit." — Derek Prince