The Voice of Reason:
Mostly, same-sex marriages are a danger only to those who would potentially participate in them, as it normalizes same-sex sexual activity and thereby makes it less likely that those with same-sex sexual attractions will practice abstinence.
As far as danger posed by same-sex marriages to heterosexual people, I really don't see any. Sure there's the contribution to the gradual desensitization of the culture to sexual sin, but I think same-sex marriage has a pretty marginal share of the blame for that. The normalization of pornography, men fathering children and leaving the mothers to fend for themselves, and the casual sex culture in general are far, far more to blame for the moral decay in this area than the minor impact that could be contributed to same-sex marriage.

Fandango:
Why do people such as yourself keep expecting homosexuals to be heterosexuals? They can’t.

The Voice of Reason:
I don't, nor did I claim to. Sexual attraction is not a decision, it's something one is born with. How a person acts, or refrains from acting, on that attraction is very much a choice.

Fandango:
Are you telling a homosexual he or she should live a life free of sexual gratification, then?

The Voice of Reason:
Yes.

Fandango:
Why? Why should they be denied the rich experience of falling in love the rest of us enjoy?

The Voice of Reason:
They are being denied nothing, I oppose all attempts by governments to enforce any sexual norms. But when it comes to morality, the only morally permissible form of sexual activity is within the bonds of a heterosexual marriage. All others, be they homosexuals or unmarried heterosexuals, are called to abstinence.