Darkness Within by Machine Head (Female vocals by SRM)

If I was asked to pick one "theme song," it would be this one.
"Pray to Music,
Build a Shrine
Worship in these desperate times.
Fill your heart with every note,
Cherish it and cast afloat.
'Cause God is in these clef and tone,
Salvation is found alone
Haunted by its melody
Music, it will set you free."
Darkness Within by Machine Head
Released 2011
Album: Unto the Locust (check it out, it's good)