If the libertarian says that gay marriage is fine so long as nobody's property is violated then the logical conclusion ought to be that the libertarian believes gay marriage should be legal.
Legal doesn't mean Lawful when discussed in context with fundamental matters of Individual Liberty. Legal and Lawful are two entirely different phenomena when the issue is judged morally in accordance with Natural Law. Natural Law is the primary foundation for moral code which establishes legitimacy in the fundamental principles of Individual Liberty as they relate to our traditional system of governance and proper human/government relations. No other worldly "legality" is legitimate in terms of defining or judging the true and fundamental libertarianism of any immoral act which defies Natural Law.
If someone who identifies as a libertarian claims that gay marriage is fine, then, he isn't a libertarian and likely understands very little of what Liberty actually is or anything directly relative to its fundamental foundation. He's a libertine at best. Libertine, btw, is not libertarian. The foundation for moral code (again, Natural Law: God's Law) that provides legitimacy to the fundamental principles of Individual Liberty and ultimately proper Man-to-Man/Government-to-Man relations must be accepted as an Indivisible whole together with its fundamental principles in order to make a legitimate claim to Individual Liberty's benefits fully. They cannot be accepted and rejected piece-meal. To accept and reject them piece-meal is an open declaration that you want no Liberty at all.
Aside from that, our traditional system of governance is religious in nature given that its founding documents and governing philosophy is premised upon Natural Law itself.
