why "good" friday?

“'God so loved the world,' John writes, 'that he gave his only son, that whoever believes in him should not perish but have eternal life.' That is to say that God so loved the world that He gave his only son even to this obscene horror; so loved the world that in some ultimately indescribable way and at some ultimately immeasurable cost, He gave the world himself. Out of this terrible death, John says, came eternal life not just in the sense of resurrection to life after death, but in the sense of life so precious even this side of death that to live it is to stand with one foot already in eternity. To participate in the sacrificial life and death of Jesus Christ is to live already in His kingdom. This is the essence of the Christian message, and the heart of the Good News, and it is why the cross has become the chief Christian symbol. A cross of all things – a guillotine, a gallows – but the cross at the same time as the crossroads of eternity and time, as the place where such a mighty heart was broken that the healing power of God Himself could flow through it into a sick and broken world. It was for this reason that of all possible words they could have used to describe the day of his death, the word they settled on was 'good.' Good Friday."
(Frederick Buechner, The Faces of Jesus (Croton-on-Hudson, NY: Riverwood Publishers, 1974), 176-79.)