It is a well-worn principle that Judaism is more about action than belief. (Furthermore, on Erev Christmas, it might be worth it to acknowledge that Christianity tends to highlight belief.)
As such, it makes sense that everything that we do should be, ideally, filtered through a Jewish lens. How we interact with others, how we treat ourselves, what we say, what we learn, everything that we do. It is our actions that make us holy (Vayiqra 19:1: Qedoshim tihyu, ki qadosh ani, says God. You shall be holy, for I am holy.)
Food being such an essential part of Jewish life (well, OK, life in general), it makes sense that the way we eat is also part of the holiness agreement between us and God.
And I'm not necessarily talking just about kashrut here, although that's important, but just as much about the food choices we make. I encourage you to think carefully not just about what you do with your body, but also what goes into it.