Namely that of giving too much emphasis on negative liberty - or freedom from external constraints. This is the basis for the Liberal concept of individual liberty.
Yet if a democracy is to survive, it cannot be possessed of random unconnected people with individual rights and liberties. As the cliche goes, freedom isn't free - and by way of Positive freedom - one has to actively partake in the self-government of ones community.
But in order to do that, a citizen individually and a citizenry in general needs to possess certain civic virtues. That means a Democracy or Republic cannot be neutral towards the values its citizens espouse, but must actively reflect those values in order to really maintain itself as a government "for the people, of the people".
And if the people in question is a Christian people who adhere to the Christian view of homosexuality; then the government(as an active reflection of this people) cannot be indifferent towards those views. Just like if democracy is to truely flourish in the Middle East, it will have to reflect the Islamic values of its citizens.
The Liberal perspective, by contrast, seems to view the government as a neutral entity that's detached from not only the values of its citizenry - but by default from its citizenry altogether. That leads open the door to forms of governance depended more on arbitrary force - even within the framework of democratic formality - "soft despotism".
This is one danger of democracy that Alexis de Tocqueville warned about a hundred years ago in Democracy in America; if citizens simply tended to their own individual self-interests without regard to the common good, then the government would have to step in to fill the gaps. Religion was a key component to putting a check on excessive individualism and turning peoples' attention towards larger issues effecting their society.
Hence why he noted the major importance of religion to democratic forms of government. It provides a common set of values for the citizenry, something that mere law cannot do.
So the fact that we even have to have gay marriage on ballots is reflective how fragmented our society has become that now we have to decide basic moral issues with the law.
The Jurist Carl Schmitt also noted that the long-term survival of any political system depends upon its ability to call upon its citizens to sacrifice their lives in time of need. Yet Liberal individualism undermines this concept, which claims a person shouldn't have to fight if they don't want to. The problem then becomes that in such a case, the system becomes vunerable and ultimately defenseless.
As he warned: "If a people no longer posseses the energy or the will to maintain itself in the sphere of politics, the latter will not thereby vanish from the world. Only a weak people will disappear."(Concept of the Political pg. 53)
Now what does this all have to do with Gay marriage? Well in order to be able to support gay marriage in the first place, one has to already adhere to a certain set of premises - and my argument here is that many of those premises are built on rather shaky grounds that have rather negative consequences for a society.
In terms of marriage; we have already seen the destructive influence of excessive individualism in terms of the breakdown of the family as the basic unit of society; and a divorce rate of almost 50%, among other factors.
Granting gay marriage would certainly be another step in that direction, since its justification is directly built upon its assumptions. Would it lead directly to animal-human marriages? [Sarcasm]Well I guess anything is possible.[/Sarcasm]
The great irony is that gays are so staunch about getting married at a time when the institution of marriage itself is becoming more and more meaningless. Which begs the question as to why its advocates are so adamant about this.
Well I'm beginning to loose my train of thought here, so I'll end it here. Hopefully I'll be to continue on this later.