For thus says the One who is high and lifted up, who inhabits eternity, whose name is Holy: “I dwell in the high and holy place, and also with him who is of a contrite and lowly spirit, to revive the spirit of the lowly, and to revive the heart of the contrite. (Isaiah 57:15 ESV)
We are instructed to be holy in God's word because He is holy. Our existence is not random, nor was it an accident. God knew who He was creating and intended each of us to receive holiness.
When we choose to worship, obey, and serve Him apart from all that the world demands, we experience the holiness of God.
Because God is holy, He is high and lifted up. This is just another expression that points to HIs magnificence. Therefore, our goal is to strive for holiness to give honor to the One whose name is Holy.
"If we comprehend what Christ has done for us, then surely out of gratitude we will strive to live 'worthy' of such great love. We will strive for holiness not to make God love us but because He already does." - Philip Yancey