Is a practical double major better than doubling down?

I want to do graduate work in religious studies and right now my plan is to double major in math (currently at UCSB) so that if my first career path does not work out, I have math as a backup. But I have also been thinking that perhaps it could be better for me to double major in medieval studies so that I have a stronger foundation. The problem is that if I do that, I am worried about what will happen if things don’t work out. I am unsure what to do.