Causing others to stumble

So I was just reading about the idea of sin on myfourwalls and looking through the comments and one of them got me to thinking.

The comment was essentially along the lines of drinking is not a sin, but when you add Paul's insight of do not cause others to stumble, the commenter deduced that you shouldn't drink alcohol in front of those that do think it is a sin. This is where I see the problem. It just seems to me that if we continue to support bad theology we can never expect change in others. I just think that it is perpetuating legalistic tendencies.

Any thoughts??