The number of Christians and cultural strength of Christianity are both declining in the United States. This decline is noticeable and is affecting church life, culture, and politics. It is also deeply disturbing to most Christians, including me.

These descriptive claims are found in my new book, A Letter to My Anxious Christian Friends, just out with Westminster John Knox Press. I will be reflecting on themes from that new book in my blog posts over the next few weeks. This is the first, exploring Christian decline in the United States.

I could now spend several paragraphs inviting a debate over whether and in what sense Christianity really can be said to be in decline in the U.S. But I won't. Suffice it to say that when one percent fewer Americans each year claim a Christian affiliation, that marks decline. When most denominations and congregations report declining membership and attendance, that marks decline. When more and more congregations close their doors forever, that marks decline. And when the youngest generation shows the greatest disaffiliation trend, that marks a decline likely to have lasting impact.

No, the more interesting question at this point is why. Why this disaffiliation trend? What are its causes?

An interesting problem in recent conversations about Christian decline is that many who weigh in appear to be defending their side in internal Christian conflicts and controversies. Undoubtedly there is some truth to their respective claims, but their polemic purposes must be considered.

For example, many conservative evangelicals have for a long time pinned Christian decline on the mainline liberals, stating that if they had held firmly to a more robust and orthodox Christianity, they would have done better.

On the other hand, many mainliners, not to mention disaffected evangelicals and ex-evangelicals, have made quite the opposite claim. For them, Christian decline is due to the excesses and rigidities of conservative religion.

Having experienced both kinds of churches, I have witnessed both kinds of disaffiliation: ex-mainliners leaving because their churches were so insipid, and ex-evangelicals leaving because they could not reconcile conservative faith with science, critical thinking, or the contemporary world.

So let's count both of those as reasons why some are disaffiliating. Here is my very tentative proposal for eight other reasons:

--Prosperity and affluence distract people from regular church attendance and reduce a strong sense of need to be in church, gradually eroding not just church attendance but Christian identity.

--The pre-modern claims of traditional Christian faith appear increasingly incredible to postmodern Americans. It has been a very long time since a majority of cultural elites found Christianity's supernatural claims, for example, to be credible. These elites dominate our culture.

--Hypocrisies and conflicts in church, when they (inevitably) erupt, don't just drive people to other churches, as in the past, but sometimes take them out of Christianity altogether.

--The fading of cultural Christianity means that fewer and fewer Americans feel any cultural or familial expectation to be in church or practice Christianity. "It was good enough for grandpa" just doesn't cut it anymore.

--American Christianity is not producing many compelling leaders, and thus the average church (as well as the Church writ large) is not especially inspiring or visionary. Many ministers play it safe in order to keep their jobs, or are simply not that talented.

--The collapse of any protection of Sunday from recreation and work, together with the gig economy, means many people are working or otherwise engaged on Sunday.

--It is harder for parents to pass the faith onto their children in a wired world in which parental influence is in decline.

--Evangelism is dead. No one really knows how to "share the Christian faith" any more in a way that connects with people, and many Christians have stopped trying.

So that's ten proposed reasons why Christianity is declining in the United States. I invite you to add your own reasons for this significant trend. In a later post I will reflect on what might be done to redress the problems the churches now face.