An excerpt rom a recent e-newsletter by James Kushiner, an editor of Touchstone Magazine:

Much of the demise of Christianity in the West occurred during a period when Christians failed to notice, or if they did, failed to respond to the shallowness of what passed for Christian faith in the mid- and late- twentieth century. Though not all Christians failed to notice it. It's just that too often church leaders chose to interpret symptoms differently, misdiagnosed the underlying malady, and offered alternative prescriptions that failed to address the core deficiency.

Church leadership prioritized, for example, "seek-sensitivity" and planned church growth by adopting cultural styles, or "modernized" and updated liturgies, or prioritized social justice or political causes of the left or the right-all the while neglecting traditional Christian formation and catechesis. Worse, they failed to diagnose or treat spiritually destructive behavior such as consumerism, individualism, and sexual egoism, and sometimes encouraged it, wittingly or unwittingly. Thus it came about that "servants of Christ" laid down their crosses and became demanding consumers of religion as self-fulfillment--Moral Therapeutic Deism as it is now called.

While civilizations seem to come and go, eventually, is there a known cure for such an ecclesial disease?

If you study the Letters to the Seven Churches of Asia Minor, you will read the Lord's invitation to repent, persevere, and accept hardship, along with his warning of judgment. So it seems that churches have a choice in the matter, and decline is not inevitable.