Monergism

Holy. A biblical term generally meaning "to be set apart." The term is used widely in Scripture to refer to a variety of people and objects alike but ultimately points to God as the one who is qualitatively different or set apart from creation. Holy may also be used to describe someone or something that God has "set apart" for special purposes. In the NT holiness takes on the sense of ethical purity or freedom from sin. The fullness of the biblical witness, then, testifies to God's holiness, understood as God's "otherness" and "purity", as well as to God's prerogative to set people and things apart for God's own purposes, together with the resulting godliness in the lives of those whom God decleares to be holy.
- Pocket Dictionary of TheologicalTerms

The loss of the traditional vision of God as holy is now manifested everywhere in the evangelical world. It is the key to understanding why sin and grace have become such empty terms. What depth or meaning, P.T. Forsyth asked, can these terms have except in relation to the holiness of God? Divorced from the holiness of God, sin is merely self-defeating behavior or a breach in etiquette. Divorced from the holiness of God, grace is merely empty rhetoric, pious window dressing for the modern technique by which sinners work out their own salvation. Divorced from the holiness of God, our gospel becomes indistinguishable from any of a host of alternative self-help doctrines. Divorced from the holiness of God, our public morality is reduced to little more than an accumulation of trade-offs between competing private interests. Divorced from the holiness of God, our worship becomes mere entertainment. The holiness of God is the [foundation of reality]. Sin is defiance of God's holiness, the Cross is the outworking and victory of God's holiness, and faith is the recognition of God's holiness. Knowing that God is holy is therefore the key to knowing life as it truly is, knowing Christ as he truly is, knowing why he came, and knowing how life will end.
David Wells - No Place for Truth, Whatever Happened to Evangelical Theology?