By the looks of it they locked them up even tho they were a real saint for the pope and the second prince to get more power and left the death relic hoping to kill them or framed them. It's kinda hard to tell with the translation issues
Spoiler
The story about the hertic saintess acutally happend in the past. So the church of the sun God has acutally been killing all the real saint and saintess for the past new generations. This current generation that cale found in the forest, survived that long was because the current pope was so greedy that he used the saint's power to only heal whomever paid him alot of money. The pope used to threaten them by training them in a coffin room full the the dead bodies of saints that they killed off, saying that if the siblings didnt obey him then they'll end up in a coffin too. So when they ran away ,they killed the Pope, hence why they were blamed for the bombing. So anyways the heretic saintess is in a similar situation as Jeanne d arc. The saintess were too powerful and the other priest wanted more power so they framed her and started to kill off the real saints when they appear to keep themselves in power. They keep the the death God's relic with the hertic saint was to seal her powers as the death and sun God power negates each other's.
Ohhh that makes a whole lot of sense, thank u
I didn't really understand about the heretic saintess?what exactly did she do with the god of death divine relic??