There is quite a lot I'd like to say on the topic, at least in critique of why John's (and purportedly Randal's) solutions are ultimately not good reasons for someone to remain a Christian; but that's not my aim today.
Here I want to offer some agreement with their assessment of deconversions and one key area of why they happen that they touched on in their final post in the series.
The idea is that of plausibility structures and how Christians need to maintain a plausibility structure through the use of their churches.
Here's the relevant part of their discussion:
JM: The third counter measure we can apply in helping believers maintain faith in the midst of a secular culture that makes them feel akin to an adult believing in Santa, is to find good communities of faith that reaffirm the biblical narrative we indwell. Authoritative communities like local churches (and to a degree the global church) act as plausibility structures, the necessary social framework for belief maintenance. Space prevents me from saying too much here about plausibility structures and the crucial role they play in faith formation. But I would encourage readers to pick up Peter Berger’s The Sacred Canopy. In it Berger demonstrates the role and importance of the church, specifically church communities, in providing legitimacy to the biblical narrative. This was true not only in the Middle Ages, but also in our own. Being around healthy, biblical communities that reinforce the truth of Christ through preaching his word, worshipping him and loving each other well, can powerfully counter the faith draining effect our secular age can have on faith formation and maintenance.I agree that modern life in 'western' or secular nations make maintaining belief in traditional religions like Christianity hard. I think that's largely for good reasons, as modern life falsifies a number of Christian moral teachings, but that's an aside. I want to talk about how staying in a church or in a connected community of believers is going to help believers keep their faith.
I want to give some anecdotal evidence to help support John's conclusion here, based on my own deconversion.
I was very active in my church, spending 8 years on the sound team, being the first to arrive on Sundays most of the time, being a trustee, and being in a small group. When I started to have my doubts about the truth of Christianity, being in the church had a socializing effect that at least could assuage my doubts in that it made me not focus on them quite as acutely as I otherwise would have. This is key, but I need to lay out some ancillary issues to highlight why.
As John and Randal get into earlier in the series, other doctrinal issues in Christianity are stumbling blocks: belief in a young earth, believing the falsity of evolution, the doctrine of hell, theories of atonement, views on the morality of LBGT relations, etc.
I didn't have all of those beliefs, but I had some of those issues that while their falsification were a big part of my deconversion it wasn't quite in the way John and Randal describe.
Their idea is that once we have those ideas tied to our notion of Christianity, the falsification of one of those ideas leads to the entire edifice of Christian belief tumbling down. Their solution is to have Christian belief be as minimal as possible (and while they don't say it, as unfalsifiable as possible). This would allow a variety of views on these 'side' doctrinal issues while preserving the number of people professing what they call 'mere Christianity'.
My main problem with this approach is that my deconversion wasn't as simple as they allege and I doubt it was for most others, especially those who go from Christian to atheist. I had explored alternative views, LBGT affirming interpretations, universalist interpretations, etc. Interpretations where the flood was allegorical, the genocides weren't actually commanded. I simply didn't find any of those views remotely plausible. Of course they are trying to address general cases, and in their view my case may be an exception rather than the norm.
What I've long suspected is that the key to apostasy is getting oneself to the emotional place where you are ready to really question the foundation of your beliefs. I believe the issues John and Randal identify have the problem of being falsifiable questions which when tied to the overall Christian belief in an individual, forces them to either abandon a shallow belief (as John and Randal believe is the general or common case), or to truly question core Christian and metaphysical beliefs and subject them to the kinds of evaluation standards we'd apply to other problems - which leads to non-theism or atheism.
The latter is what happened to me, and it's why I'm now an atheist. But how does this relate to my point of agreement with Randal and John about churches being vital to maintaining belief in a secular age?
It boils down to the fact that humans aren't completely rational animals.
Let me be clear, I think on a purely rational appraisal of the evidence for and against any specific religion (say Christianity) or even theism in general, one is going to end up at least as a non-theist.
But we are not purely rational, we are swayed by emotion, instinct, and our social context. When you're in a church and part of your social circle is strongly influenced by the commitment of ones belief to certain doctrines, as it will be in a church social community - you're going to be inclined to rationalize away the problems with your view.
In my own case, I had two very distinct sets of social groups with near zero overlap. I had my church friends and my geek friends. My wife and I were closer to our geek friends, but we still liked our church friends. In fact not long before apostasy we were involved in a close church small group for I think 2 years.
What changed? I took a temporary work assignment to live in another country, Randal's own Canada. Because my wife had recently been laid off before the opportunity arose, she got to come with me and live there while my employer paid for accommodation and meals the entire time.
I worked a minimum of 50 hours a week, often far more, so we weren't really going to church services on a Sunday, as that was one of the brief times we'd have to spend together. Plus there's the whole "what church do we go to in this foreign place?" question. Especially since a lot of churches in that part of Canada had services in French rather than English.
It was then that my doubts intensified significantly, and I was "socially free" to explore them without any recluse to my church and small groups to provide an emotional need to anchor myself back into belief when the fundamental questions came up.
I think that in this case, I was left to just work through the rational side alone, and per above, I came out a non-theist at best. By the time the assignment had ended and I was back in the states, I tried to talk to my small group and pastors, but near zero progress was made. I tried to go back to my faith as my wife didn't immediately deconvert, but that process eventually convinced her that Christianity was false as well, and we had little desire to attend services as that process wore on. Even while I was an atheist trying to go back, my wife was somewhat disillusioned with the conservative aspects of our church anyway (especially given the questions I was raising about hell and LBGT issues). Those issues caused cognitive dissonance before, but we had stayed previously for the people.
In fact we really missed some of the people, especially those in our small group, but the apostasy made us not really want to interact with them, our main connection effectively severed. What's more is that we had our own social group that consumed most of our time, and not long after our first child was on her way.
I'd like to think that had I not taken that business trip, I'd still be an atheist today, it just would have made the journey take longer and be more painful. But if I'm honest, I can't say that with complete certainty.
If we had our first child while still attending church, it would have increased the social costs of apostasy by orders of magnitude, depending on when the doubts would have really taken hold of me vs. the age of my daughter. There is a reason the most effective ministry for bringing new members to our small and dwindling church was the children's ministry.
All of this relates to what I like to think of as 'the psychology of apostasy', which is an often neglected aspect of both atheistic arguments and apologetic discourse. I think I can present the best case for atheism possible, that on a logical and evidenced based evaluation of the situation, one will come out a non-Christian and a non-theist; but if the social costs for the recipient of this are too high, there's always going to be an out - a logically possible way for them to reconcile their beliefs somehow.
And if I'm 110% honest here, the inverse is likely true. I don't think that one can make a logical and evidence based case that really gets one to the truth of Christian (or Islamic, Judaism, etc) theism; but if there was, if the social costs were high enough for a secular or atheist person, they can rationalize their way into staying in their unbelief as well.
That fact should probably inspire some humility in all of us who engage in these conversations.