Lateran Liberi don't feel lesser than Sankta
You are getting the wrong idea from Patia, who was born and raised in Iberia. She does not reflect the feelings of Lateran-born Liberi, which is why Fiammetta does not understand her.
(The latest trailer for Laterano shows a racially-diverse children's school where the students all wear the same uniform, they sit among each other without segregation, and they're all equally cheerful.)
Iberians practice the Lateran religion but most of them never see Sankta or the city of Laterano. Iberians form exaggerated visions of what the city and its angels are like.
Patia immigrated to Laterano as if she thought she was ascending to heaven to become one of God's angels.
She's not even quoting passages from scripture that say such a thing is possible. This is entirely an idea cooked up by Iberians, not Laterans.
When she gets to Laterano, she learns that most Sankta are just really human goofballs. Goofballs who have no idea how to give new immigrants halos or the ability to use Patron Firearms.
And the most serious and knowledgeable Sankta are really uncomfortable about the subject of what makes the Sankta special, because the Sanktae's secret origin as "Sarkaz transformed by a machine" is always threatening to turn the world against them and plunge the angels back into the endless cycle of hatred and violence that plagues the Sarkaz.
"Sorry not sorry, but we don't want to talk about (or even KNOW, for most of us) why we can't make you an angel because we really don't want to become demons again. Please just enjoy the paradise we've built for ourselves from our blood, sweat, and tears."
