lets be honest though, while most of what the government throws at us is a bunch of rhetorical bullshit, some of it is true, smoking produces carcinogens, and eating can be rather intense, and there are saftey risks while being high, though they are not as beefed up as they want you to think.explain that.

then explain to them that they are your friend and that if something like that is going to come between that, then they are less of a friend to you than you are to them, and ask how it hurts them that you do it. If they say that stuff like they dont like to see you "harm yourself" in that manner, give them something along the lines of that the religion they practice creates a barrier from having an understanding with them in the friendship and that you feel that their strong attachment to something that hold dear is hurting you because it is affecting your friendship.

that should really enlighten them as to how you feel and also inform them that smoking isnt as bad as they really think. And as a thought, just dont bring the subject up around them if at all possible.

A reasonable person would be fine with this.