The music on Sufjan Stevens' 2004 album Seven Swans is a much more quiet, introspective affair than his other releases. The instrumentation is more sparse, consisting typically just of an acoustic guitar, or banjo accompaniment. The songs are mostly based on religious themes, such as the transfiguration of Christ and Abraham. This song in particular, my favorite on the album, relates to the great sacrifice that Jesus made on the cross to atone for the sins of the world. Other parts could possibly be about the guilt that Judas felt for his betrayal of Jesus, or could also possibly be Sufjan admitting fault for sins he himself had committed, and expressing his gratefulness for Christ's death so that he could be saved. While not being a particularly religious person myself, this is still powerful stuff and Sufjan is able to portray his religious beliefs without sounding as if he's preaching to you.