If we’re saying that public office, or at least high public office is barred to people of a particular faith, or people who have a faith but can leav… - Kate Forbes

I do think that those people who are withdrawing support from her, I'd ask "why did you support her in the first place"?
Because I don't think what she's saying is new, and I think it shows a level of unseriousness of many people who engage in political activity and commentary, where they don't take things seriously in terms of "why am I supporting this person"?

Now, I admit that often I don’t understand the "whys" of God’s plans. Maybe it's because I don’t know myself as well as He does. He knows the exact number of hairs on my head. I don't. Or, maybe it's because I'm not God and never will be, and so I don’t quite grasp his reasoning.
Maybe it's because I am ambitious, young and female. I have a degree from Cambridge University, worked in politics and I'm now employed on one of the best fast-track schemes in the business world. Education, hard work, and stewarding our talents within the parameters of Scripture are commended in God’s Word.

[Forbes is] entitled to her view [but same-sex marriage] has become part of the culture of the country around the United Kingdom over the last ten years.