It's probably too obvious to mention:

Were You There When They Crucified My Lord?

however there are a variety of verses for this classic spiritual from slavery times in the Deep South. And new verses can be added. The folk process is always timely. Anyway I love this song anytime of the year as it is a solemn yet comforting musical meditation on the very basis of Christianity. Christ actually loved us so much that he gave his life in such a profoundly painful way so that we might live eternally. Now, that is truly awesome! I remain in awe of His sacrifice and this song brings me back to that important revelation whenever I sing it.