Open Mouth, Insert Foot

I think I am going to stop trying to have intelligent conversations with people. Every time I try, an argument always erupts. Honestly, I don't really feel that it is my fault either. I am a very opinionated person, so when I see somebody is talking about a subject that I care about, I say something. It's not bitchy, and I always start it off with "In my opinion..." or "I think that..." But there is always somebody that doesn't agree with me. And that is perfectly fine. Everyone is entitled to their own opinions and I respect that. I NEVER tell someone that they are wrong, or how they feel is stupid. I just say "I agree" or "I see where you are coming from but have you considered..." I don't think that this would be a good opportunity for someone to start yelling at me! I am just expressing how I feel, I know that there is always going to be somebody who feels the opposite as me.
Yesterday, I got into the topic of making our town be able to sell alcohol. We are the only city in our area that is still dry. I said that no matter where you sell alcohol there will ALWAYS be drunk drivers. But I feel that if Quinlan were allowed to sell alcohol, the amount of drunk drivers could possibly decrease. When a drunk has to drive 15+ miles to get more alcohol they are putting more people's lives in danger than if they could just go down the street to get it. If someone is drinking and wants more alcohol, they are going to get it whether they have to get it for themselves or not.
One girl commented on my statement saying that alcohol is the last thing that our town needs, because we are already out of control. and if "I" would stop drinking and driving, people wouldn't have to worry about drunk drivers. NUMBER ONE) I DO NOT drink and drive. I always have a designated driver! NUMBER TWO) this girl doesn't even know me. We have never met, and I didn't even know that she existed until this comment was made.
I told her that I have a husband and two children and I would never do something as irresponsible as driving drunk. She followed that comment with "having a husband and children doesn't make you an adult and you saying that it does just proves that you are not an adult."
That has got to be the worst thing that I have heard in a long time. No, having a husband and children doesn't make you have the same maturity level as an adult...but she doesn't know who I am. How can she proceed to judge me as if she does? I put an end to it and by saying that I was talking about making our city wet and she started changing the subject to disrespect me and criticize my parenting skills. And that was the end of the conversation from me.
Things like this have happened to me more often than I would like. Maybe I am acting like a know-it-all when I try talking to people. But in this case, I was not the one to start being hateful. This happens to me a lot when I try having intelligent conversations. I guess I will just keep my mouth shut when something doesn't pertain to me...even though it was an open question, directed to the public.
As my best friend said to me regarding this situation, "You should know better than try to have intelligent conversations." Oh geez, is she right or what?!