This position is completely untenable. The state should not be involved in the religious practices of a church.
However, the Church should not use the state to prohibit private activity, in which, consenting adults engage and undue harm is not caused to another individual.
Homosexuality is not natural.
Neither is God, but I do not hear many people arguing against his existence, nor his goodness, on the basis that God is not natural. The agrument that just ignorant; many things are "unnatural," but that does not make them worng.
You obviously don't care about the society in which your children and grandchildren will live. You should care, because you have an obligation as a citizen to pass on a healthy, safe enviornment for normal development. Teaching youth that two men smearing excrement on each other is the same as a nuclear family is morally and concretely wrong. However, one has to acknowledge objective truths and concrete morals---and to face reality instead of dwelling in relative libertopia.
What about reaching for the optimum instead of encouraging vices. What benefit will it bring to our children? You encourage that kind of behavior?
Q: Why should society be involved in personal issues such as (marriage, drug use, homosexual sex, etc.)?
A: People exist in society not by convenience but because people are social by nature.
We do not exist well in a vacuum. Part of the function of our society is to maintain norms of interaction that will allow us to survive. We call these norms our culture. Historically, cultures must be based on concrete fundamental truths. They can't be based on the whims of the moment or they will fall apart. In fact, historically, those cultures that have lasted the longest were based on concrete fundamental truths and they fell only when the societies stopped enforcing those rules. To date, only one culture in all of human history has been able to reconstruct itself after it fell, and that was because it returned to those concrete fundamental truths and cherished them until it could regain its land. I'm talking about Jewish culture and Israel.
America was founded on concrete fundamental truths. France was not. Both governments had similar ideals, but America had a culture to sustain those ideals and the government has been working here for over 250 years. You can't say the same for France because their culture is not based on concrete fundamental truths. If America lets those truths go, we will go the way of France, which is headed for the same fate as Babylon or Ninevah or Rome or any other ancient culture.