OH
Paulin has been attending sermons at Good churches, in case they're reporting people for not showing up. He didn't really understand until now, though. Until this spell showed him with certainty that he can trust this cleric. That's what Lawful Good means. Lawful meaning honest and trustworthy and Good meaning trying to help him and on his side because good is on the side of everyone. He doesn't have to keep asking questions or worry about his safety. The cleric of Iomedae is on his side and trustworthy because– there is no 'because'. It's true because it's true. The cleric of Iomedae is someone he can trust because that's what cleric of Iomedae means. Lawful Good is Lawful Good.
"You should cast this on everyone, Select."
(Were he thinking more clearly, would recognize an enchantment spell and be suspicious of sudden changes in feeling, though he still wouldn’t recognize the specific sensation of being under charm person. That gets cast on people useful enough to want favors from, or sometimes ‘useful’ enough to want ‘favors‘ from. Not on the useless dregs who wash out early with nothing but cantrips, around half of a first circle spell, and enough debt to last a lifetime. But he isn’t thinking clearly, anxious about oh-no-cleric and then overwhelmed by the wholly unfamiliar feeling of ‘a trusted friend and ally’)