There are several topics, ie gay marriage, evolution, certain political issues, that are related. Every time a new thread is started the same old comments are regurgitated again and again. It gets annoying to those of us who aren't interested in re-arguing the same point over and over. Instead it makes more sense to add your comments to existing threads.
If you are unsure if a thread exists, simply use the search feature, type in the topic and find the one that fits.
As forum members it's up to each of us to make sure we're keeping the board as clean and efficient as it can be. Having the same topic in multiple threads does not serve this purpose.