Wherefore gird up the loins of your mind, be sober, and hope to the end for the grace that is to be brought unto you at the revelation of Jesus Christ; As obedient children, not fashioning yourselves according to the former lusts in your ignorance: But as he which hath called you is holy, so be ye holy in all manner of conversation; Because it is written, Be ye holy; for I am holy. (
1Peter 1:13-16)
Holiness is the life one lives, after salvation, as empowered by the Holy Spirit, as a witness and a praise unto the Lord our God, Jesus Christ. It is a walk, talk, dress, attitude, and thought process which the Lord has called to be set apart from the world, as a witness to and against the world, convicting them of their sins. It is the empowerment of a believer to live in a fashion that is pleasing unto the Lord.