There is something to be said about saying something you believe in without feeling the need to defend it or argue for it. Controversial arguments are generally very interesting and hardly ever productive.
Most online flame wars (through email, facebook comments, twitter comments, blog comments etc.) work on the premise that person posting the last response wins. In most online flame wars, your decision of not replying is often considered synonymous to your not having a reply.
The online heckler often expects you to shout back to quiet him down. Once you do that, you have started a controversial argument and it doesn’t matter what the logical outcome of the controversial argument is, the heckler wins.
All a heckler needs is a lot of free time and the persistence to keep replying.
You cannot win this game if you play it by it's conventional premise.
But you have an option of not playing the game to begin with; or taking a decision of not replying even when you have a reply; or quitting the arguments in the middle even when you’re not the person with the last response.
Just say what you truly believe in. If that triggers an argument; make your points. Once you’ve made your points (or voluntarily chosen not to make them) leave the topic and the argument. Say something else. A brand new post. A brand new thought. A brand new idea.
The hecklers can continue heckling about what you said. They will eventually get tired and stop when they realize that you’ve already moved on to something else. After all, In the long run the hecklers and the critics just don’t matter as much as you think they do.