Couple points:
1- If your whole argument that marriage is a sacred covenant that only means on thing to everyone you're living under a fucking rock. Marriage means something different to absolutely everyone who gets married; for some it means dedication, to others it means any one of the infinite definitions of love, to most of the world it means producing offspring, to a lot of Westerners it means someone to be with for the next 7 years (average length of a marriage in America). In a lot of places in the world marriage means an non-consenting young girl being signed over from her family to an older man who she knows little about.
The definition of marriage throughout history has never been a concrete thing, there have been competing definitions across cultures since the beginning of civilization and I would be beyond shocked if that ever changed.
Saying "OMG BUT BUT THEY'RE CHANGING THE DEFINITION OF MARRIAGE!!1" Is like complaining about the release of Vanilla Coke; Classic Coke isn't going anywhere, you're just uncomfortable with change.
2-Yes, you do have the right to your own opinion on this matter. Keep in mind though that as one of the stragglers to get on board with such a black and white issue you're going to get called out pretty damn hard for sharing you're ill-conceived thoughts; it's not the 80's.
3-If something that means everything to millions of people, while at the same time makes absolutely no significant impact to your life makes you feel the need to speak up and speak against it... Well you're either a bigot or a fucking idiot.
4-I know everyone loves pictures so here are some clearly unnatural animals having gay sex with each other.
