God is set apart by His Holiness more than by any of His other perfections. God uses the term “holy” in many ways: with it, He describes Himself; Lord Jesus used the word; the third person of the Trinity holds it in His title, Holy Spirit. All persons of the Trinity ascribe themselves to be holy. Holiness is twofold in character. It is absolute transcendence and supreme majesty. In this sense, it is hardly a moral attribute because it expresses His transcendence over everything.
When theologians speak of God as the “Holy other”, they are speaking of Him in His holiness as one who is separated and, therefore, distinct from us. It is also used to designate His absolute moral purity. In the presence of a Holy God, one sees their sin (Isaiah 6:1). One reason we have no clear perception of ourselves is because we have no clear vision of God.