The appalling cost of forgiveness to God is shown in the cross. God does not simply say, ‘Never mind,’ to the sinner, pretending that sin never happened or that it is of no significance. We wouldn’t accept that concept of forgiveness for ourselves, so why should we force it on God? True forgiveness involves facing and recognizing the great pain and distress caused by the offence—a process for which the cross is perhaps the most powerful illustration known. The love of God for his people is expressed, not in a soft and sentimental way, but in the context of the seriousness of God’s hatred for sin.
— Alister McGrath, from Understanding Jesus, p. 109