Assuming that you're setting agnostic, a forgotten realms Tormish paladin could certainly be holier-than-thou:
Torm became the master of Celestia after the heroic self-sacrifice of the legendary Tyr (who perished decades ago when defending the upper realms against an overwhelming demonic incursion). He now shines as the beacon of pure law in the cosmos, and stands as the most civilized and civilizing force in the pantheon. Truth, loyalty, and a steadfast devotion to a righteous cause are his gifts to his mortal followers, and he is an inspiration to many of his fellow deities as well.
The Dead God, Haramathur, The Guardian in Stone, the Eternal Watcher:
Taking a page from Sir PTerry's Great God Om here, one of the best holier than thou approaches can be "My god sacrificed his form for us and we are here. What has your god done that's so impressive?" as well as "I don't need miracles to believe" can both approach a very snooty tone.
Haramathur was a guardian god who was tasked during the Dawn War with the protection of the Astral Sea against incursions of creatures from the Elemental Chaos. He had no enemies among the other deities, who recognized him as a force whose power protected them.
In the last years of the Dawn War, Io’s violent death caused a rift between the planes. Haramathur realized the only way to prevent the primordials from using the rift to invade the Astral Sea was to close off the way with his own essence. He sacrificed himself by turning himself and everything around him to stone to seal the rift. Few individuals know Haramathur’s role in these events. The deities try to limit any knowledge of what happened because they fear that someone might seek to restore Haramathur to his original form, and hence restart the war.
In general, most LG deities don't behave in a "holier than thou" way. My recommendation, if you want to make it into a proper plot point, is to have Pelor actually be an arch-fiend. Logic defined here. Therefore Pelor's church, ostensibly good, would absolutely encourage Sister Bertha better than thou (Ray Stephens, referenced by John Ringo in Princess of Wands).