If she was with you when you talked to the knight and completed the quest then no, she is gone for good. If she was in the party she will wait outside the church and ask you if you plan to go along with helping this God. If you say yes then she will leave, if you say no then as a thank you she will mind control the nuns and force them to have a orgy with you and her, but you lose out on the Paladin class. This is not a bug, it's a feature of the game from before, i kid you not. There are certain points in the game that if you havent played your cards right will cost you party members, Permanently. To avoid this lil pickle just leave the hoe out of your party when you pick up the quest, yes it is that easy. Add her back while you do the quest and then remove her again before you turn it in. Bada bing bada boom. Also sorry for your loss.