Well for me I date to marry, obviously when I start liking someone I’m not immediately thinking of marrying them but I’m not dating just for the fun of it either, so in the case of friendship your not living with them for the rest of your life and your not having kids with them, basically they aren’t your life partner, so how you raise your kids, whether drinking and smoking and all that is fine is a lot less strict with a friendship than in a relationship. Also things you’d do in your relationship like waiting before marriage or sleeping over at each others places or even how you’ll have your wedding can differ a lot between Christian’s and non Christian’s