Yes. Non-Christian men and women should be allowed to marry. In churches, or in synagogues, or in mosques, or on the courthouse steps, or by a justice of the peace, or by the captain of a ship or by "Elvis" at funky little chapels in Las Vegas or common law marriage for that matter. The issue is societal norms, not how and by whom couples are married. The societal norm is that marriage is and should be between a man and a woman. The biological reason and the advantage that confers to a society are rather obvious. Homo*_*_*_*_*_*uality and same-*_*_*_*_*_* unions deviate from that societal norm and have a social stigma attached.
What seems to be at question, at least in my mind, is this: should this be the case? And if no stigma should be attached to same-*_*_*_*_*_* marriage, then shouldn't it follow that married homo*_*_*_*_*_*ual couples have every right to adopt or undergo in vitro fertilization procedures, propagate, raise a homo*_*_*_*_*_*ual family, and forward that lifestyle as a "normal" and equally acceptable alternative to the traditional family? Traditional family values say "no". Traditional Judeo-Christian morality says "hell no".
Children deserve at least a chance to have both a mother and a father to raise them. Each parent, mother and father, brings something unique and very important to the proper social and emotional development of a child. Deviate from this and the chances for healthy social development of that child are significantly compromised. Sure, death and divorce are realities. And single parent families are an unavoidable consequence. But is it optimal for kids? No, absolutely not. And every single parent knows this all too well.
Choose homo*_*_*_*_*_*uality for yourself if you wish. You have that right in a free society, and you have the right to expect civility, dignity, acceptance and tolerance for having made that choice. But don't then expect to propagate it as the "norm" for American society. Do not expect our society must then also openly approve and put forward same-*_*_*_*_*_* marriage as a "normal" lifestyle to then be taught to our children as an equally acceptable alternative to traditional family values. Our society says it is not so, and for good reason. While one can "define" deviancy down, the consequences of deviancy remain and take a terrible toll on society. There will always be a stigma attached and it will not go away at the voting booth.
A mother and father are not, for example, free practice and teach kids polygamy, or incest, or rape, or cannibalism, or whatever as acceptable alternate lifestyles. These are deviant and destructive behaviors of varying degree, and are not tolerated by civil society. So, in short, and being absolutely frank about it, consenting homo*_*_*_*_*_*uals may feel free to "blank" around with each other, just don't think they can "blank" around with traditional family values, teach our kids deviant behaviors by example, and then, expect or demand the right to gain loving approval from our society for doing so. Sorry, it's a non sequitur.