Dang, you put me on the spot.
I wouldn't say that drinking in and itself is a sin. As we know, the bible says that drunkenness is a sin, and of course it's possible to drink and not get drunk. HOWEVER, (here's the controversial part where I'll probably catch a lot of flak) I do strongly believe that Christians shouldn't drink at all. I have many reasons for that... I don't want to write a whole essay here. But I've put a lot of thought into this, and long story short, I believe that as it says in 1 Cor 10:23, "All things are permissible, not all things are beneficial."
There's a lot more I could say about this, but it's a topic that could be a thread of its own.