I'm not generally a fan of "slippery slope" arguments, because it is far from obvious that just because X undesirable social problem exists, it does not necessarily result in Y. For example, it is not obvious to me that forbidding teacher-led prayer from public schools necessarily produced the social upheavals which followed that 1962 Supreme Court decision. It seems far more likely that the social currents of the times produced the men who produced the decision, which did more to symbolize the unraveling social consensus than to create it.
That being said, it seems obvious to me that we humans seem to move naturally along a progression from being shocked by sin, to being mildly uncomfortable with sin, to failing to even notice it anymore. Consider the progression of three popular shows featuring homosexual characters: In the early '90's, Ellen was considered avant garde and was critically acclaimed for the "Puppy Episode," in which Ellen Degeneres' character "came out." The show, however, flopped in the ratings afterward. But 1998 brought us Will and Grace, a show in which two of the principal characters (Will and Jack) were openly homosexual. This show raised protests (and ratings!) initially, but eventually became so much a part of the landscape that NBC placed it on its "Must See TV" line-up on Thursday nights. Will and Grace ran for 8 seasons, garnering 87 Emmy nominations and 16 wins. It finished in the top 10 shows on TV for 5 of its 8 seasons.
Now we have Modern Family. What's interesting about this show is that it centers around a fairly ordinary suburban family. Dad (Ty Burrell) is a real-estate agent while the mother (Julie Bowen) is a stay-at-home mother. Mom and Dad celebrate their 17th anniversary during one of this season's episodes. They worry about their kids, work on their marriage, and encounter all of the challenges of modern life. Her father (Ed O'Neill) is married to a much younger Latino woman (Sofia Vergara), who has a son by a previous marriage, while her brother (Jesse Tyler Ferguson) is one-half of a committed gay couple who have an adopted Chinese daughter. So within one show there is racial diversity (a good thing), a recognition of the realities of divorce and the difficulties of blended families (also a good thing), and the celebration of healthy, long-term committed marriage and the importance of Mom being home with her children (all good things). But there is also the persistent, never quite stated, but still presented idea that a committed gay couple has just as much right to be called a family as any other family structure. It's not the "out and proud" vibe of a show like Will and Grace, or weird coming-out drama like Ellen. It's more of a plea: Please love me, respect me, and regard me as equally a member of the family, the Modern Family, along with you. On top of all of this is some really great writing and some hilariously funny bits, all serving to make this attempt at intellectual and cultural reformation go down with sugar instead of salt.
Which strikes me as tactically brilliant. Humor disarms far more effectively than argument, and sympathetic portrayal does far more to advance the cause than impassioned protest. Moreover, I believe that this show is a reflection of the current state of American culture, just as surely as Engel v. Vitale was. If my prognostication skills are working, I think it will not be long before gay marriage and gay adoption seem simply to be part of the postmodern, post-Christian landscape of American life. Shows like Modern Family are helping that cultural transformation along, making us laugh our way through the gradual, but still radical, reshaping of our country.