Unfortunately for you - marriage is a "civil affair" and not a religious one. You cannot get married without a civil marriage certificate. So do not confuse the civil part of marriage with the religious one. Many people, myself included, were married in a civil ceremony, not a religious one. Many "Christian" countries, it is normal to have two ceremonies - the legal civil one and a religious ceremony. So don't confuse your Christian beliefs with legal requirements for a "marriage".
And since you are so against same sex marriages, my recommendation is that you do not engage in one; however, for that 1.7% of the population to whom it matters, they why should they be denied, because other people do not like or agree with it? Live and let live.