I was raised protestant, but turned my back on it. Honestly I'm all for gay marriage. If you find someone else that makes you happy; so be it. Be it a man or woman, that is irrelevant. My best friend of nearly 20 years happens to be gay. Personally, I can understand why the vast majority of churches don't recognize it. It seems to be mostly fundamentalist christians (A concept which seems to be localized almost exclusively in the US) that are opposed to this.
As far as polygamy goes, in our predominately monogamous society it is generally frowned upon. Personally, I believe if you haven't committed youself to one person, then by all means date or bang as many people as you want. I am engaged so I don't mess around anymore. Monogamy, in and of itself, is an interesting concept. Very few animals exhibit monogamous behavior. Somewhere around 3% in mammals, I think. (I'm sure someone is thinking about birds now. Ornithological monogamy is more often than not social than exclusively sexual.) But I digress, as long as you're not killing people or molesting children, do what makes you happy. But let others have that same freedom; All too often is our society plagued by double standards.