What should I write in a christmas card for boyfriends parents?

I have known my boyfriends parents for a few years, got closer to them this past year, but I have only been dating Nick for four months. His parents are both good cooks, and they built a pizza oven in their backyard this summer so I bought them an infused olive oil. I know them through our church so I got a card that is somewhat religious, which they will like. They have been super welcoming to me, and never complain about when I am over at their house (which is pretty much every day). I absolutely love spending time with his family. By the way I am in college, so I am going to address the card with their first name and I would like the rest of the card to sound proper as well, but also very kind.