The constitution does not address equal protection for persons of deviant sexual behavior. If it does, please show me where.
We agree (I assume) the First Amendment protects you specifically on the basis of your religion. The Fourteenth Amendment protects you on the basis of your race, but it does not mention race: No state shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any state deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
There are those who would apply the liberal interpretion of equal protection to apply it to homosexuals. The loophole in your argument is that it does not protect marriage against the liberal interpretation of equal protection.
Here's a related example: the Equal Rights Amendment failed and therefore men and women are not required to be treated equally. Yet Title IX has wrought unfair damage upon university athletic programs.
I am all for equality, but it has its dangers.
Marriage is protected by government (yes, steve-b) for the sake of the children. These protections are wasted on homosexual couples and so we must make that distinction even if in other areas we treat homosexuals as having equal rights.