I don't claim to be an expert on the gods, but any child might know that Selune wars ceaselessly and tirelessly with Shar.
If Kiel had been "rescued" as a child from a temple of Shar, I can easily imagine a community of Selunites protecting and raising her in the faith. Devout and powerful priestesses are valued by both goddesses. The Selunites would be able to save and cleanse the child while causing on-going anguish to their enemy temple. Selune, whether in her role as merciful mother or vengeful hunter, would approve.