On The Side Of The Angels Meaning

(idiomatic) Fighting for or supporting that which is good, just, or benevolent.

Example: 1999, Melvyn L. Fein, The Limits of Idealism: When Good Intentions Go Bad, Kluwer Academic/Plenum Publishers (1999), ISBN 0306462117, page 55:
  Each likewise portrays itself as on the side of the angels, as fighting the good fight against adversaries who are neither decent nor fair.
2009, Mark Pallen, The Rough Guide to Evolution, Rough Guides (2009), ISBN 9781848369382, unnumbered page:
  But when it comes to the conflict between compassion and cold reason, he is on the side of the angels: […]
2012 January 15, Stephen Thompson, "The Reichenbach Fall", episode 2-3 of Sherlock, 01:16:03-01:16:12:
  Sherlock Holmes: Oh, I may be on the side of the angels, but don't think for one second that I am one of them.