Democrats: My shot-in-the-dark prediction for 2028 is that either Shapiro or Whitmer will be nominated. Shapiro's Jewish and I don't know what Whitmer's religion is.
She's answered "Christian" before in candidate/elected official questionnaires but never anything more detailed than that. As far as personal church affiliation goes any searching on her social media only shows her going to black churches in de facto campaign events. She did say this back when she was a State Senator though:
So I'm guessing her religious identity boils down to something like "Culturally Christian and theistic but without any firm denominational or church affiliation."
EDIT: She also said this in an interview:
https://www.legalnews.com/detroit/1427879What is the best advice you ever received?
"Everybody's important, no one is inherently more important than another person. It's my father's less religious riff off his mom's belief God made us all, we should respect one another and there is something beautiful in everyone - even if it is simply their smile, you should try to find it."
Which kind of backs up that conclusion.