The characteristics of a church stuck in Christendom are many:
1. They are Attractional in nature. Whether the draw is a rock band or a gold fish, the way to engage the culture is to ask them to come on our turf. Back in the 1950's, American culture was almost monolithic. I know there were differences between New Yorkers and Southerners in Alabama; differences between Black culture and White culture, but when it came to Christianity, the church had a similar culture across the board. Whether they were high or low church, you could still expect the clergy / laity distinction. You could expect basically the same kind of music being sung in all the churches and the church buildings pretty much all looked similar to each other: wooden pews, stained glass (if you had the money), big pulpit, preacher in a suit, hymn books, steeples, an altar, organ and piano. The church didn't have to do much to adapt to the culture, because the culture pretty much was shaped by the church as an institution for hundreds of years. The church and the state together enforced each other's laws as partners and the general populace took on it's likeness. In America, the marriage between the state and the church was dissolved and it didn't take long before the culture began to be shaped by other influences that were more persuasive than the church. The government, the spirit of the age and technology began shaping the culture and shortly after the end of the second great awakening, the church lost its power to influence the culture more than these other influences. A century after the second great awakening, there would be a cultural revolution that would forever change American culture and the church has been trying to figure out how to adjust ever since. Without the power that it once had during the great awakenings, the church had to mimic the culture to stay "relevant".
The American culture began to be shaped by the industrial revolution, the sexual revolution and now the information revolution. Americans became independent rather than interdependent; consumeristic rather than loyal to principle; addicted to fast results and convinced that bigger is always better (thanks to super-sized McDonalds meals and Walmart). The 60's brought on a totally secular, sexually deviant godless morality and with all these changes, the church just adapted by trying to shape their churches the same way:
Christians emphasize private spirituality and devotion more than community and accountability.
Christians made the church into a provider of religious goods and services for religious consumers.
Christians have had a love affair with a prosperity gospel that offers quick results for your best life now.
Christians have bought into the Mega churches and their leaders as the only kind of churches worth emulating and listening to.
Church leadership has adopted a CEO kind of leadership approach and have turned churches into Christian businesses.
This approach was and is attractive to the people who remain in the old Christendom. All you had to do is pick your niche and "do church" that way. You'll get the crowd that you shape your church services to attract. Although there are now more mega churches today than there ever were in the past, Christianity has not spread and over all church attendance has shrunk considerably in the last 20 years. This is because the church growth methods have only worked in attracting the small piece of the population pie of Christendom that is ever decreasing. Most churches have only grown by doing church better than other churches and sucking members from other churches to themselves.
This needs to change as the population grows more and more away from a Christianized culture that will come to church if you invite them and give them the product they're looking for. The emerging culture is not looking for anything that the church is offering, even if the church keeps marketing itself like it has been doing.
The church needs to stop trying to be attractional and needs to become infiltrational. The way salt preserves meat is by spreading the salt all over the meat. You don't put a big block of salt in the middle of a piece of meat. The same is true of the church. The church cannot expect to set up shop, open its doors, have a nice program and expect people to show up any more. They need to start being salt and get themselves in every crevice of the culture bringing the gospel to people.
This means that the church will have to change many of the things that it has become addicted to. It will have to lose the professional clergy as the only official leadership. It will have to lose the consumerism and start calling for commitment to discipleship and community. It will have to stop operating by bringing people to church and start bringing church to people. It will have to stop authenticating its own validity by large buildings, programs and crowds. This may be too much for some and they will not change. Their churches will eventually die and lose their precious buildings.
By the word "Reforming" I am speaking of "reviving and renewing" The essence of this kind of reformation is the enrichment of understanding God's truth, arousing the affections Godward, and increasing devotion to Him. - J.I. Packer