On the one hand, this is part of a long term trend toward secularization in the USA. On the other hand, it is a consequence of the politicization of Christianity over the last 25 years; the growing tendency of Christianity to be linked to right wing politics.
Secular progressive and liberal commentators who I normally agree with are rejoicing over this news. My feelings are more mixed. On the one hand, it means that the extremist reactionaries who want to police everyone's souls are already losing much of the power and influence they enjoyed for so many years. On the other hand, as numbers and church attendance decline, the fanatics in every denomination have more influence, accelerating rates of decline, and further marginalizing any kind of serious religious conversation.
The long tradition of Christian progressivism, that began together with the labor movements and campaigns to end slavery and now embraces LGBT rights and feminism, is almost forgotten. Christian Socialism, the Social Gospel movement, the religious dimension of early feminism, Liberation Theology, all of those movements are largely forgotten by the public. The message that the exploited and marginalized were not only fully human and fully citizens with dignity, but beloved by God with sanctity is now twice buried in popular memory. It was first buried by communism and its militant secularism, and then again by triumphalist capitalism at the end of the 20th century. Christianity is now thoroughly identified with conservative and right wing politics and social identity.
I wonder if a religion that proclaims a new heaven and a new earth can really be called "conservative." I wonder if a religion whose leader was executed for blasphemy and sedition should really be considered a spiritual bulwark for any political or social order. I wonder if a God who so explicitly favors the poor and the cast off can really be relied upon to bless the success of the already privileged and powerful.
If it's all about preserving the "traditional family" (whatever that is, and I assume they mean the 19th century Victorian model and not the much older and more durable model where husband and wife worked as equals out of necessity, and children worked in fields or in shops as soon as they could walk), then maybe the religion that works better is the old Roman religion of hearth and ancestors where the home was literally sacred and the family patriarch was a priest and judge in life and a god in death. That religion had everything a Fox News commentator could want, patriarchy, strict sexual regulations, and even a virginity cult.
I'm not so sure that a religion founded by wandering homeless celibate men and women who all forsook homes and families works quite so well for preserving social order and hierarchy.
Napoleon said that nothing works better to keep the poor in line than the threat of eternal damnation. Bismarck believed that the Church was the most effective instrument of the State for keeping social peace. Marx described the priest as the landlord's best friend. Right wing Christian leaders have been all too willing to play that role of establishment social and cultural cop (which is why the plutocracy loves them, "anything to keep the yahoos voting our way" has long been the attitude on Wall Street). And now a public that's been left holding the bag and expected to pay the bill now that Our Betters have spent the inheritance at the roulette table has lost faith and patience. What a surprise. They see the Church as but another collection agency, another enforcer, another branch of the Bank; the same one that went broke selling bogus mortgages and gambling with credit default swaps.