Responses
I definitely think that Seong She's kids aren't his biological kids, and he's practically a virgin, who probably got SA'd in some cult or something. I do really hope that the story doesn't take a virgin uke knows nothing x promiscuous seme route as I find it cliche, and AGGRAVATING! but maybe uke is gay and since his father was christian he found out and hated his son, also told the church so they SA'd him to remove the gay away? Or was he SA'd by the "christian priests" in the childhood and that's why he ran away and cut off contact? There can be many possibilities.
This is a real shot in the dark, but I wonder if Seong Su’s kids aren’t actually his biological kids. Like if someone high ranking in the cult had a secret kid, and Seong Su’s Father, wanting to curry favour, offered to have Seong Su take responsibility. It’s then possible that the biological parent later wanted to take back their son, but had to go about it in a convoluted way in order to maintain face. Maybe convince the cult/community Seong Su was an unfit father, and together orchestrated a fake death to cut Seong Su out.
The fact that Seong Su is so tight-lipped about the mother(s) and seems to have always been the sole legal guardian, I’m guessing the mother(s) don’t want to be associated with the kids/wanted their identities kept secret. Seong Su might not even know who they are.