WARWICK: "[Christianity and Islam] are only east and west views of the same thing." (4.102)
Warwick is a lot more open-minded than you might expect a medieval nobleman to be.
CHARLES: "The famous holy oil they talked so much about was rancid: phew!" (5.29)
Throughout the play, things that are supposed to be "holy" are demystified.
DUNOIS: "She will find that God is on the side of the big battalions." (5.52)
Dunois's overall religious philosophy seems to be that God lets us make our own luck.