Even as Jesus dies, there is a miraculous reveal of who Jesus is. As he is revealed, the people are filled with awe and even the centurion testifies that he is the son of God.
The ripping of the curtain is a sign of that which is complete (atonement) and the resurrection of the saints is perhaps a glimpse of the general resurrection to come as well as a glimpse of the resurrection of Christ himself.
Readings from this service:
Exodus 26: 31-37
Psalm 18: 4-7 & 9-11
Matthew 27: 45-54