Leon Morris on the wrath of God

"Modern men find difficulty with this aspect [wrath of God] of the Old Testament teaching, in part at least because they have so well learned that God is love. But it is important to notice that this was a truth known and valued by men of Old Testament times. They apparently did not find it insuperably difficult to combine the ideas that God loved them and and that He hated all evil and would punish it severely ...

But in view of the fact that we have both truths expressed, and expressed very strongly ... it seems better to say that divine love and the divine wrath are compatible aspects of the divine nature. There is a divine wrath, but if we may put it this way, it is always exercised with a certain tenderness. Even when he is angry with man's sin God loves man and is concerned with his well-being in the fullest sense. There is a divine love, but it is not a careless sentimentality indifferent to the moral integrity of the loved ones. Rather it is a love which is a purifying fire, blazing against everything that hinders the loved ones from being the very best that they can be." (Morris, Leon. The Apostolic Preaching of the Cross. Grand Rapids: Eerdmans, 1965. Print. 175-176)