Tickle shows the context of the Great Reformation began much further back than Luther nailing his theses to that door. Around 140 years prior, the Reformation cracks began to split when two simultaneous and very political elections of popes occurred in 1378. The notion of who has or what is the authority came to the forefront, and would continue to be called into question in other events, such as astronomer and clergyman Copernicus writing (but not yet publishing) his theories that the sun was the center of the universe. Gutenberg's invention of the printing press helped spread those challenging theories to the common man along with ancient writers like Homer, Pythagoras, Plato, Aristotle, Euclid, etc. which were brought into Europe a century before by Greek Orthodox scholars who fled Constantinople upon its capture by the Ottoman Turks. What is clear historically is that the Great Reformation was no more started by Martin Luther himself than the Great Emergence can be pinned down to (or on, depending on your bent) any person, say a Brian McLaren or Tony Jones or any other famously attacked emergent Christian.
The main two off-shoots of the Great Reformation, which we are can agree, were the notions of sola scriptura et scriptura sola or "only scripture and scripture alone" and the priesthood of all believers. That authority structure replaced the conflict and mess of authority in multiple popes, and began the process of deep-rooted investigation into scripture as the foundation of Christianity, which naturally led to further conflict and the beginnings of what we know now as thousands of Protestant denominations. While the founding fathers of Protestantism infamously and bitterly disagreed and halted conversations by spinning off into their own congregations, the leaders of the emerging movement are at least trying to open and conversant in this new re-formation of institutional Christianity. But I am getting ahead of myself.
So as the Great Reformation had political, cultural, scientific, and technological breakthroughs which significantly influenced Christendom, what have been the breakthroughs that cracked the foundations for this re-formation now being called the Great Emergence? Charles Darwin (evolution) and Michael Faraday (electromagnetic discoveries) make the shift from post-Reformation to peri-Emergence, with Faraday having the more significant impact technologically and later culturally, and Darwin forcing the church to emerge doctrinally by conservative denominations forming fundamental theological statements to claim true Christian belief. Freud and Carl Jung came along with scientific theories of the mind and unconscious, which influenced people like Joseph Campbell to challenge the doctrine and principle that Jesus and Jesus alone is "God with us" and salvation for all humankind is exclusively through Jesus alone. The advent of radio and television became the printing press of the Emergence re-formation and therefore institutional Christianity now had to compete with these thinkers and discovers through a new and widespread media.
Where Tickle goes into great detail is the chapter called "The Century of Emergence". Briefly, the list of influences includes Einstein and Heisenberg and Uncertainty, which badly woulds sola scriptura and the subsequent the rise of Pentacostalism with deep roots in egalitarianism and the influence of historic African-American spirituality to respond to the scientific challenges on spiritual authority. Going on, the invention of the automobile directly affects the basic infrastructure of Christian community, which was rooted in the nuclear and extended family. The Sabbath was replaced by "Sunday drives" and Grandma, the spiritual matriarch, was left in the dust. This doesn't even touch on how World War II and "Rosie the Riveter" affected family and gender roles in church and society. Add in influence of Alcoholics Anonymous (which brought in small groups and showed that healing and support did not come from the pulpit but from others who are just as broken, as well as continue the voice of being spiritual but not religious), the Drug Age, and Buddhism, you will find all sorts of threats and challenges to the institutional church. Finally we have the technological explosion of the 80's, 90's, and into the 21st century where individualism and instant gratification perpetuate throughout all life and culture. This is a bombarding of a Christianity that has already changed significantly three times prior.
The point of this whole context is that Christianity has had no choice but to emerge, and no matter how much some want to deny it, we are all emerging. There isn't a current and prevalent denomination that hasn't emerged within the past century which shows the re-formation of Christianity is occurring. Phyllis Tickle shows clearly the how and why, not if and when. And, as someone who likes the big picture and finds himself most comfortable in the center, I found this particular chart most interesting:
The four quadrants of this chart are Liturgicals, Social Justice Christians, Renewalists, and Conservatives. They used to be considered denominationally as Catholics/Anglicans/Lutherans, Methodists/Mainline, Pentacostals, and Evangelicals/Fundamentalists respectively. But those became somewhat erroneous categorizations and the current quadrilateral is used. The axes are defined as followed.
those placed above the horizontal axis, in general, are so because "what one does religiously is more central to his or her understanding of Christian living than is what one believes doctrinally." Conversely, those below, in general, are so because "what one doctrinally believes is more central than what one does religiously."
The top vertical axis represents the tension between faith and works. If given a choice on Sabbath between mass or a Habitat for Humanity build, again in general a Social Justice Christian would choose, with some regret, Habitat for faith without works is meaningless, while a Liturgical would choose mass, also with some regret, because works without faith are empty.As can be seen in the image above, what the Great Emergence has done is create "a gathering center" where the axis lines are blended. Individual Christians are now emerging as well as the institutional church, where the authority of the quadrants is no longer held firm and Christians are finding value in both orthodoxy and orthopraxy, faith and works, old and new, conservative and liberal. Statistics show we aren't staying loyal to denominations or churches. Membership numbers are down not just because people aren't attending churches, but because people aren't identifying with just one church or one community.
So while the emerging and emergent church leaders have received a ton of praise and flack for the conversation, what is being made clear is that this re-formation of the church is indeed a great emergence both institutionally and individually. As I started to say earlier, what the emerging conversation is doing is giving opportunity to re-form, renew, and grow anew the authority of Jesus in an entirely opposite manner than the Great Reformation forefathers. While Luther, Calvin, Zwingli, Buce, Schutz, Bullinger, etc brought Christendom into subject of the authority of scripture, they also tore apart many opportunities for unity in Christ. Where we, as the Church, go from here only God knows. But as we continue to emerge and gather in the center, we have an opportunity to focus on the cross that connects us all.