Religions in the United States grow and shrink because of immigration, births, deaths and many other factors, but a recent report from the Pew Research Center offers a chance to look in detail at which religions are gaining and losing members the old-fashioned way: by recruiting new members.

Pew took a look at which religions have gained and lost followers when people change faiths, and we used its data to run the tape forward and see which religions would be on the rise if people kept switching at the current rates. This model isn’t a projection of the future (because it doesn’t take into account other factors); instead, it’s a way to measure the pull that religions are exerting on potential converts at present, by taking today’s trends to their logical conclusions.

In its 2014 Religious Landscape study, which surveyed more than 35,000 Americans, Pew asked respondents about their current religious practice and the tradition in which they were raised. Pew found that the group of Americans who are unaffiliated with any religion gained the most members, on net, from religious churn. Although only 9.2 percent of Americans reported being born into a religiously unaffiliated household, 22.8 percent described themselves as unaffiliated by adulthood. The share of Americans who are Christians, as a whole, dropped 15.0 percentage points (from 85.6 percent at birth to 70.6 percent at present). Pew highlighted some of the most dramatic swings in the table below but also collected data on seven additional denominations.

I want to share with you some recent correspondence to a friend. He is the head of a mission agency and has been visiting a PCA church. He was impressed enough to consider membership and asked for my honest assessment of the state of the PCA. Here, with a few edits, is what I shared with him:

My friend, the local church that you are attending is a fine representative of one part of the PCA, but clearly it is not representative of the whole. Your church would be on the “progressive” side of things and would represent a majority of the younger pastors and the churches that are growing. It is hard to tell, however, if that church represents a majority of the PCA as a whole. If it does, it is barely a majority. The denomination, as a whole, is clearly divided between traditionalists, progressives, and neutrals. The traditionalists are highly committed to Confessional fidelity and are often worried about perceived doctrinal drift.

The progressives are frustrated by the perceived cultural isolation of the denomination and the lack of Gospel impact upon the larger culture.

The neutrals are happy (even proud) for the PCA’s biblical fidelity, are at a loss for why their churches are not growing, and perceive that the traditionalists and progressives fuss too much about too little.

Theological zeal and institutional loyalty keep the traditionalists engaged despite their concern about the church. The progressives are increasingly concerned that the church cannot move forward without controversy, and segments of this wing occasionally talk about whether it’s worth staying — even though most votes go their way at the General Assembly level. The neutrals always hold the swing votes at the General Assembly level — they can be frightened into action by the traditionalists but generally are more inspired by, and aligned with, the progressives.