What does it mean to be holy? Holiness is about God, not us. It is about nurturing a relationship with him, while also showing the  world who he is  through  our lives. Holiness, as Peter seems to indicate, is rooted in being transformed by Christ's love, and experiencing an overflowing of that love into everyone around us.

Holiness is the key to  the fruit of the Spirit. Peace and holiness are connected, according to Matthew Henry and Charles Wesley. There is no true peace without holiness. They also comment on how the stress of our salvation is laid upon our holiness. Without holiness, as the writer of Hebrews notes, no one will see the Lord.

1. Call for Holiness

Therefore, prepare your minds for action; be self-controlled; set your hope fully on the grace to be given you when Jesus Christ is revealed. As obedient children, do not conform to the evil desires you had when you lived in ignorance. But just as he who called you is holy, so be holy in all you do; for it is written: "Be holy, because I am holy." Since you call on a Father who judges each man's work impartially, live your lives as strangers here in reverent fear. For you know that it was not with perishable things such as silver or gold that you were redeemed from the empty way of life handed down to you from your forefathers, but with the precious blood of Christ, a lamb without blemish or defect. ... Now that you have purified yourselves by obeying the truth so that you have sincere love for your brothers, love one another deeply, from the heart. For you have been born again, not of perishable seed, but of imperishable, through the living and enduring word of God. 1 Peter 1

2. Nature of God
Psalm 89:35 Once for all I have sworn by my holiness; I will not lie to David.

3. God's people witness of His holiness
Ezekiel 20:41 As a pleasing odor I will accept you, when I bring you out from the peoples, and gather you out of the countries where you have been scattered; and I will manifest my holiness among you in the sight of the nations.

Ezekiel 39:27 when I have brought them back from the peoples and gathered them from their enemies' lands, and through them have vindicated my holiness in the sight of many nations.

4. Called to maintain our holiness in Christ-as a witness of God
Romans 1:4 and designated Son of God in power according to the Spirit of holiness by his resurrection from the dead, Jesus Christ our Lord,

2 Corinthians 7:1 Since we have these promises, beloved, let us cleanse ourselves from every defilement of body and spirit, and make holiness perfect in the fear of God.

Ephesians 4:24 and put on the new nature, created after the likeness of God in true righteousness and holiness.

1 Thessalonians 3:13 so that he may establish your hearts unblamable in holiness before our God and Father, at the coming of our Lord Jesus with all his saints.

Hebrews 12:10 For they disciplined us for a short time at their pleasure, but he disciplines us for our good, that we may share his holiness.

Hebrews 12:14 Strive for peace with all men, and for the holiness without which no one will see the Lord.