The First Letter of Saint Peter is an epistle written by the Apostle Peter to the Christian Churches of Asia Minor, in the letter the Apostle writes about the fraternal love and life in holiness, in the letter he expresses this sentence: "Be holy, because I am holy "1 Peter 1:16.
In this exhortation, holiness has a religious connotation that is identified with life in grace, that is, the righteous life: "Do to others what you would have them do to you" Matthew 7:12.
The expression about holliness would be also an allusion to Piety, within the context of the letters of the apostles. Piety in the old testament is Mercy, but in the new testament it also means devotion. In short terms, holiness, in Peter's letter would be meaning a "devout rectitude."
We found a similar text to the expression in 1 Peter 1:16, in Matthew 5:21-28, "Be perfect as your heavenly Father is perfect." Holiness, Retitude, Mercy are not virtues, they are spiritual gifts, perfections.
The goal of holiness is not happiness, holiness is not practiced, it is "live" is "inherited".
The virtue is practiced, the gifts are living. The gifts are living because we grow, and are inherited because we received the gifts from God.
Recall that the purpose of Holiness is communion, life in common. The opposite of communion is the double life, the hiding maneuvers, the insincerity. For a person who lives in communion, "what you see is what it is".
Live in communion, is to live without masks, is live to improve the world, is to project our love not to ourselves but to everything created by God. That is the genuine love of God, the Agape, the Charity.
Live in holiness is to live the commandment of perfection and excellence, not the commandment of love (the love is a genre) but the commandment of charity.