Be holy as God is holy

“As obedient children, do not be conformed to the passions of your former ignorance, but as he who called you is holy, you also be holy in all your conduct, since it is written, “You shall be holy, for I am holy.” (1 Peter 1:14-16 ESV)

Holiness: The most basic meaning of the word holy is to be "set apart" or "dedicated" to God. Biblical terms translated "holy" or "holiness" (qadosh, hagios) carry a strong secondary connotation of moral purity. Holiness is not primarily about moral purity. It's primarily about union with God in Christ and sharing in Christ's holiness.

Bring holiness to completion

“Since we have these promises, beloved, let us cleanse ourselves from every defilement of body and spirit, bringing holiness to completion in the fear of God.” (2 Cor. 7:1 ESV)

You shall be holy to God

“You shall be holy to me, for I the Lord am holy and have separated you from the peoples, that you should be mine.” (Lev. 20:26 ESV)

“For God has not called us for impurity, but in holiness.” (1 Thess. 4:7 ESV)

Therefore…

“Therefore, if anyone cleanses himself from what is dishonorable, he will be a vessel for honorable use, set apart as holy, useful to the master of the house, ready for every good work.” (2 Tim. 2:21 ESV)

“But you are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into his marvelous light.” (1 Peter 2:9 ESV)