While I watched with the expectation that the participants would mostly discusses religious or ethical arguments for and against SSM, the arguments tended to confuse issues of civil (or secular) rights with religious belief. Perhaps that was inevitable given that the only persuasive arguments against SSM are grounded in the exegesis of religious texts; which is not to say there is always a clean division between secular and religious laws. Sophocle's tragedy Antigone (written in the 4th century BCE) is precisely about the conflict between state (polis) and divine law. I simply live in a pluralist society that has decided (as the non-establishment clause of the first amendment seems to make clear) in favor of accommodating many conflicting religious and ethical systems in a secular legal framework. For the arguments Morse and Gagnon make to be plausible, that secular system would need to become an explicitly more Christian one. This disagreement over first principles partly explains why neither side at Skyline convinced the other of anything, and why Brian Brown and Dan Savage (despite a delicious dinner together, which Savage dubbed "Bigot Christmas") will never change each other's minds either. Maggie Gallagher even admitted to Mark Oppenheimer that no evidence will ever change her mind.
And even if somehow the evidence showed, conclusively, that same-sex marriage were good for children? Gallagher would still be dissatisfied: “Nothing could make me call a same-sex couple a marriage, because that’s not what I believe a marriage is.” (Oppenheimer, "The Making of Gay Marriage’s Top Foe," 2012-02-08).
Evidence (i.e., quantitative science) is irrelevant when the disagreement is over the irrational beliefs (I do not mean that pejoratively, because beliefs are by definition matters of trust or faith, neither of which are rational) from which the two sides build their arguments. Gallagher even makes that clearer in her response to Oppenheimer's article on the Savage-Brown Dinner Table Debate.
The disagreement is precisely over our commitment to maintaining a secular, open society as opposed to one governed by a particular institution's (or coalition of such institutions) received (and sometime radicalized) interpretation of a specific religious tradition. Yet, the debate hardly ventured in that direction with the closest graze coming from Robinson. He revealed (1:20:00+) that he's advised his ministers to provide only blessings (i.e., the marriage sacrament) to couples and leave the civil marriage certificate to the town clerk. His compromise is similar to the view that everyone (hetero- and homosexual) should get a civil union and then go to a religious institution for a marriage or other rite if the couple so desires.
Morse provided the clearest example of this confusion between secular and religious bureaucracies when the debate turned briefly to discussing divorce. To her credit, she said no-fault divorce should be repealed and then launched into a personal story that ironically illustrates the double standard she holds gays and lesbians to. When she divorced and remarried, she had to petition the Catholic Church for an annulment before she could be married in Church. Her point seemed to be that she couldn't force the church to change its views on marriage and divorce. The point to which she seems entirely oblivious is that she was able to get a divorce from the state and then get a marriage license from the state while at no point did the state's secular, immoral, hedonistic divorce laws compel the Catholic Church to recognize her bigamist marriage (in the eyes of the church she was still married to her first husband and therefore an adulteress and bigamist). The same should apply to same-sex marriages.
John Corvino pointed to the contradiction in the opponents' fixation on SSM while doing nothing politically to curtail no-fault divorce. The same point arose during Dan Savage's debate with Brian Brown; Savage got it exactly right when he said the National Organization for Marriage (NOM) and others don't push for restriction or bans on divorce because they would then be attacking the rights of a large majority (married heterosexuals) rather than a vulnerable minority (the LGBT community).