Protection from white and from red means the following things:
Can't be damaged by anything white or red.
Can't be enchanted or equipped by anything white or red.
Can't be blocked by anything white or red.
Can't be targeted by anything white or red.
Wrath of God does not damage, enchant, equip, block or target the Crusader, so the Crusader's protection doesn't do anything to prevent it being destroyed by the Wrath.
Wrath of God does not damage, enchant, equip, block or target the Crusader, so the Crusader's protection doesn't do anything to prevent it being destroyed by the Wrath.
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Lightning Bolts don't kill creatures. State-based actions kill creatures.
http://forums.mtgsalvation.com/showthread.php?t=489747