Im a practising Christian, and Ive noticed that there seems to be a great deal of hypocrisy on the part of other practicing christians, even within my own parish. Most of them are the types to preach against the evils of drugs, but they're all a bunch of piss heads. The Local parish club on a Friday nite is just the same as any other pub, bar or club - everyone's pissed, yelling, smoking obscene quantities of tabs... and this is all considered perfectly acceptable - in fact it's actually condoned by the local church. This from people who are against the destruction of Gods temple, your body.
Now I think theres something fundementaly wrong with that.
So now I just avoid/ignore all moral issues involving drugs and religion. I find the only person who knows whats right in those circumstances is yourself. If your friend has had a go at you smoking weed, be honest with them and yourself. If you have no intention to give up, tell them that, and make it clear that you are comfortable living the way you do. If they are a good friend, theyll respect your views. Just dont rub it in.
I have a friend who is a devout Hindu, and he objects to consuming drugs himself, he doesnt eat meat, he doesnt drink... I respect his views, and he respects my decisions, even if he considers them unwise. Basically we dont force anything on each other, and we get on with living and having a good time.
Cos thats what its all about.