LANE: So he doesn’t like me, he’s not gonna call. It’s not the end of the world. I’ll live. I’ll go on. There’s always college. Unless my parents get their way, and then it’s “I take thee Jesus to be my lawful wedded husband.”
Lane is suggesting that her parents want her to “marry” Jesus, or devote herself entirely to her religion. Catholic nuns are called “brides of Christ” for the same reason, but despite Mrs. Kim wanting Lane to (rather implausibly) attend a convent, there is no equivalent in the Seventh Day Adventist religion. Adventists don’t promote celibacy, even for people in pastoral roles in the church, so this doesn’t really make sense.