There is no "fundamental right" to homosexual marriage Luis. For a scholarly opinion on that statement, read Standhart v Superior Court of Arizona, Nov 2003.
That's funny.
When cornered, most conservatives would agree that rights are not granted by a document, nor are they subject to another's opinions...they simply exist, with the Constitution protecting them. That's until the moment that some "right" is brought into question which "offends" our sensitivities, then we immediately launch into all sorts of goobly-gook about whether this fundamental right, or that fundamental right exists or not.
Here's one right you do not have...the right to deny others their right to life, Liberty, and the pursuit of happiness based on YOUR biases.
There will be some sort of recognized civil union for same sex people, you can't stop it, the Church will not be forced to either recognize these marriages, nor perform them, and the institution of marriage will survive in spite of the best efforts of heterosexuals to destroy it.
It's all happening right in front of your eyes, and wishing that it wasn't will not make it go away.
Nearly every right confered to a legal spouse via marriage can be obtained through an attorney, and contracts, the few exceptions being Social Security benefits, and next of kin privileges in health care and surviving spouse duties. I have no problem with any person willing to enter into those agreements with another, gender arrangement be damned, you seem to have issues.
I also understand that whether gays marry or not in no way cheapen my marriage...I'm not so insecure to fear that. I know one more thing that you are not willing to accept..."they" are not going away.
Now, can you detail by what power the government denies Mormons the right to polygamy as a part of their religious observances?
Or will you continue to avoid answering the difficult questions?