Sin casts contempt on the majesty and greatness of God

The language of it is, that he is a despicable being, not worthy to be honoured or feared; not so great, that his displeasure is worthy to be dreaded; and that his threatenings of wrath are despicable.

The language of sin is, that God’s displeasure is not worthy that the sinner should regard it. The proper vindication of God from this language is, to show, by the experience of the event, the infinite dreadfulness of that slighted displeasure. …

The majesty of God requires this vindication

When the majesty of God has such contempt cast upon it, and is trodden down in the dust by vile sinners, it is not fit that this infinite and glorious majesty should be left under this contempt; but that it should be vindicated wholly from it; that it should be raised perfectly from the dust wherein it is trodden, by something opposite to the contempt, which is equivalent to it, or of weight sufficient to balance it; either an equivalent punishment, or an equivalent sorrow and repentance. So that sin must be punished with an infinite punishment.

Sin casts contempt on the infinite glory and excellency of God. The language of it is, that God is not an excellent being, but an odious one; and therefore, that it is no heinous thing to hate him.

—Jonathan Edwards
The Works of Jonathan Edwards, vol. 2, 567.