Wanted: An Explanation of the Dead and Dying

Uninformed and undeveloped thought:

I was reading this book on Christian history today, and got to hear a brief overview of the origins of the non-Western church, something I always knew existed fairly early on but have never been taught anything about.

I still don't know enough to write anything educated on the topic (so I'm not), but I did want to pose the question: how do we make sense of churches that die?

Like the early Chinese church or Arab church.

And churches that still die today.

I'm not so much talking about why churches in a society might have more trouble winning converts during a particular era and certain church bodies might lose membership or even fold. But at a larger scale, why is it that some societies with a Christian witness watch that witness actually essentially die out?

Are they the corrupt and faithless?
Or are some of these churches actually faithful?
Do we blame the leaders or the regular people or the missionaries that first evangelized the area or the outsiders that perhaps just watch or at worst don't even look?

Is it an issue of theology?
Practice?
Prayer?
Distractions?
Persecution?

What causes the death of a "solid" church? Of a "weak" church? What defines each?

And where is the Holy Spirit's life-giving power?
Or sin-convicting voice?
Or sustaining comfort?

Why do churches die?

Why are there people groups that know about Jesus, where Good News should be taking root and leading to reconciliation and restoration left and right and then all of a sudden BAM-- it's gone. Did these people ever understand the gospel to begin with? (Do any of us?)

Why does God let this happen?

And are we doomed to endless cycles of converting and reconverting? Sure, God is inefficient ( a good thing), but he also wants the gospel to have a presence everywhere-- a presence that transforms its surroundings. Is there any hope for the gospel to actually be more than a fairy tale but something God continues to work out in our midst? How do we invite him to do that, considering the fact that that work has stalled time and time again among various peoples?

Is the answer to simply shrug and refer to the parable of the sower? "Those people didn't actually accept the gospel in a meaningful way." "Those people let the Good News of Jesus be choked by the weeds of conflicting cultural priorities." "Those people never had the gospel presented to them in a way that hit-home."

Does the church have to operate in cycles? And is this more of a sine wave? Or is there any consistent direction we're going? What does that mean if there's not?