Holiness is the first and foremost characteristic of God in the Old Testament – from it proceed the two corollaries of love and wrath: love towards what is good and compatible with His holiness, and wrath towards what is corrupt and unholy in His universe. This is the most basic biblical teaching about the character and reality of the God who is there – He is not ‘only love’, He is utterly holy and consequently capable of moral discrimination and hence of holy wrath and righteous judgement.
(Peter Lewis)