This is the famous song that Jesus mouthed while dying on the cross.
He was barely able to utter the first line of the poem, "My God, my God, why have you forsaken me?" The Gospel writers were able to distinguish these words from the violent gasps coming from Jesus as his chest heaved up and down on the torturous wooden beams. It would seem that Jesus was not just quoting lines for future gospel books, but rather he was reciting Scripture as a means to endure the betrayal, the abandonement, the cruelty, the embarassment, the grief, the burden of sin.
It seems to me that the straggle of disciples that heard Jesus utter this inital line of a psalm then watched Jesus mouth the next 31 lines. The daringly hopeful lyrics end with a triumphal: "He has done it!" which could easily be yelled out as "It is finished!".
The OT provides much of the rich background to Jesus' mission, identity and self-understanding. It also gives us potent insight into Jesus' relationship with his Father up in Heaven, if you take the time to reflect upon the psalmic phrases.
Read through Psalm 22 again, slowly, and picture Jesus on the cross, body broken and bleeding, pierced and impaled. With a soul and mind that is sharp yet sad, he mutters these words - in the spirit of defiance against evil, in the spirit of loyal love to his Father, and in the spirit of unyielding hope for the people he came to rescue and restore unto righteousness.
While we were yet uninterested in God, he was hoping and working so that we might someday "experience and proclaim his right way of living in a perpetually wronged world".