Our Lord, from the Cross, quotes Psalm 21's opening verse, "My God, My God, why hast Thou forsaken me?" Right off, the Scripture scholars tell us, this means that He intends to place the whole of the Psalm in their minds. This Psalm is one that describes the Passion of Christ rather accurately: the dividing of the clothing, the piercing of the hands and feet, and so on.
This means, however, that Our Lord also intends the end of the Psalm which speaks of praise for the faithfulness of God. The Psalmist generally ends Psalms of Lament with such praise.
Christ bore for us the weight of our sins. This was the weight of the sins of the world -- all of them. If one mortal sin separates us from God, imagine the weight of them all. Many of course, will rush in to remind me that Christ always had the beatific vision. It is true that many theologians have held that through the centuries. However, it is not something de fide tenenda. Personally, I cannot tell you if He did or did not behold His Father's face at all times. I do think there is merit to the other theologians, who remind us that He emptied Himself, as St Paul teaches us, taking on the form of a slave. In other words, He became man, and man does not share the beatific vision in this life. Another point in favor, as we recall, is the teaching of the Angelic Doctor that it is not possible to sin or experience temptation in Heaven, because once we behold God, we could never choose an false good. If Christ beheld God the Father at all times, how was He tempted?
For our sake, Christ may have felt complete abandonment from His Father. Rather than deny His divinity, this strengthens it! What other so-called god of the ancient world would empty himself that completely? This is a ridiculous thought to non-Christians. God becomes man!
In his kenotic state (the state of emptiness), Our Lord was able to sense separation from the Father. This is how He loves us, that He emptied Himself that much!
Another side to the story is that the sensation of abandonment by God, is not reality. We know that the Father did not abandon the Son (or us for that matter). In the spiritual life, as we feel the most distance from God, we are, ironically, the closest to Him. So many spiritual writers remind us that it is when we feel the wood of the Cross in our own lives, that we are closest to Christ. It is as though, because the embrace is so close, we can't see Him.
When we feel abandoned by God. we remember that He is probably closer than we imagine. The cry of Christ from the Cross also teaches that it is OK to express ourselves honestly to God. So many think it would be irreverent to speak to God in any way other than grovelling. God wishes us to be friends and more sons in the Son. A son can tell his father how he is feeling. It is when we are most honest with God that our prayer is most pure.