The fundamentalist Christian subset is not nearly as powerful in Canada as it is in the States. That's not to say it has no say; just that most people choose a more middle ground than that.

Medical benefits are not as huge as they are in the States, either, but supplementary insurance (the stuff that pays drug plans and dental, for example) can still be a problem for same-sex couples. Granting them common-law status took care of quite a bit of that problem, because common-law couples have the right to access their spouse's supplementary insurance if the spouse puts them on it.

It is a very emotional issue for many Christians, because you're right - there's an element of "we're having to defend our way of life against immoral sinners! Yuck!" Also, many Christian couples see this as a personal attack on the institution of marriage in itself and on their own marriage - watering down something that should be meaningful until it's lost what made it special to them. I truly do not understand that point. My marriage is special to me because Piet and I have created it together. It has a religious significance, a very serious one - but someone else's marriage having a different religious significance will not change the import of mine.