From The Jesus I Never Knew by Philip Yancey:
“This time only, of all his prayers in the Gospels, Jesus used the formal, distant word ‘God’ rather than ‘Abba’ or ‘Father.’ He was quoting from a psalm, of course, but he was also expressing a grave sense of estrangement. Some inconceivable split had opened up in the Godhead. The Son felt abandoned by the Father.
“ ‘The hiddenness of God perhaps presses most painfully on those who are in another way nearest to Him, and therefore God Himself, made man, will of all men be by God most forsaken,’ wrote C.S. Lewis. No doubt he is right. It matters little if I am rebuffed by the checkout girl at the supermarket or even by a neighbor two blocks down the street. But if my wife, with whom I’ve spent my entire adult life, suddenly cuts off all communication with me – that matters.
“No theologian can adequately explain the nature of what took place within the Trinity on that day at Calvary. All we have is a cry of pain from a child who felt forsaken. Did it help that Jesus had anticipated that his mission on earth would include such a death? Did it help Isaac to know his father Abraham was just following orders when he tied him to the altar? What if no angel had appeared and Abraham had plunged a knife into the heart of his son, his only son, whom he loved? What then? That is what happened on Calvary, and to the Son it felt like abandonment.”