Honestly, I find that line of thinking offensive. I don't use my signature to promote my personal beliefs or convictions. I celebrate Christmas, go to church regularly, and my son is intact (the first male in several generations on both sides of the family).
It really isn't my place to make assumptions and judgements about others' decisions based on signatures. If you want yours to proclaim your beliefs to the MDC community - great!
My signature is there b/c my DS likes the animated smilies and I picked ones that were cute. We don't even have a dog but he loves that one so I leave it on there.