A friend asked me recently to articulate what I believe to be the primary difference between ancient and modern Christianity, which I argue is the matter of what it means to be the Church. By the Church, I mean the mystical and visible Body of Christ, the understanding of which is the pursuit of ecclesiology as a field of study.
All analogies have limits, and I propose the following analogy with that in mind. I use it to illustrate an important set of distinctions, not to create a new ecclesiology based on an analogy that's moderately useful. That's how too many people get into the barren and boring fields of heresy with Trinitarian doctrines, after all.
It occurs to me that the key differences between the ancient and modern Christian understandings of ecclesiology are similar to the key differences between ancient Christian and modern secular understandings of marriage.
One of the differences between the ancient Christian understanding of marriage and the modern secular understanding of marriage is that the ancient Christians understood marriage as being truly an exclusive matter. There was one person who was truly a person's spouse, and that fact didn't change because one of them left and took another lover and they were recognized as married by the local officials.
In the same way, the ancient Christian understanding of the Church was that there is one true Church which is exclusive. Just as you're either in a marriage to someone or you're not, they believed that you were either in the Church or not. Large numbers of people saying that they too believed the Apostles' Creed, all the while teaching what was heretical, did not dissuade them from their belief.
This does not mean that they lacked nuance in their thinking about who might be in the Church, but it does mean that they didn't reduce it to a matter of superficial doctrinal agreement alone, or a matter of mystical participation alone, or a Neo-Pelagian sort of insistence that people who act virtuously in the classical sense are somehow in the Church by virtue of those virtues.
And there is another, related difference between the ancient and modern ecclesiology, at least in a fair number of cases (albeit not in all cases). It too has an analogous situation in the modern understanding of marriage.
Let's consider an example. Let's suppose that two people get married, and then get divorced. They both then marry different people, and after a while divorce their respective 2nd spouses. And then they marry one another again. This does happen on a rare occasion, at least in the United States.
And it can happen because the modern conception of marriage is that it is something that can be dissolved, and then a new marriage can arise in its place, and then that can be dissolved as well, and then the old marriage can be re-established. Marriage is no longer understood as a lifetime commitment by common cultural definition, though it may be an aspiration for some.
In much the same way, the modern conception of the Church is no longer one of a lifetime commitment. The modern ecclesiology does not insist that we need to remain faithful to the one true Church (whatever we believe it is) throughout our lives, but rather that we need to find a church community that suits our preferences, and that we can leave and move to another one as we find it convenient to leave or find it appealing to go to the one we prefer more.
There is a third difference between the ancient and modern ecclesiology that I want to mention, and the marriage analogy can also work to explain it.
The ancient understanding of marriage was that it was explicitly hierarchical. Whether that hierarchy was based on clan, rank, or gender, there was generally some sort of explicit hierarchy in marriage, just as there were generally explicit hierarchies in most areas of life in the ancient world.
Modern marriage, on the other hand, is increasingly without any explicit hierarchy. That doesn't mean that there are no hierarchies in practice, or that implicit hierarchies don't form anyway based on power imbalances in the relationship, of course. It just means that there's no common recognition of a particular hierarchy as culturally normative. And often that's because there's a contemporary cultural imperative to eschew hierarchies.
In the same way, modern ecclesiology attempts to eschew (or at least minimize) hierarchies. Many newer Christian communities are run democratically by the members in some form or another. Pastors sometimes even dress down relative to the formal standards of attire, de-emphasizing their powerful role in the hierarchy that's inescapably implied by having a pastor in the first place.
As with marriage, this don't actually eliminate the hierarchies. It simply neglects to formalize them while allowing the pretense of a non-hierarchical relationship between those who take on the role of shepherd and the rest of the flock.
Of course, the ancient ecclesiology has an explicitly defined formal hierarchy. There are bishops who are the shepherds, and they delegate to priests, who must then faithfully implement the bishop's instructions for the parish. And there is a Pope who functions as the primus inter pares (first among equals) for the college of bishops.
Lest anyone get the wrong idea, I point out these differences not in a triumphalist way, but rather in a philosophical way. Though I'm a Roman Catholic and I adhere to the ancient ecclesiology, I'm well aware that many other (and some newer) Christian groups also agree with the ecclesiology I described, either in whole or in part.
Some have an ecclesiology that is almost the same as mine (e.g. Eastern Orthodox), others have an ecclesiology that has some strong similarities, but also important differences (e.g. Anglican Continuum), and yet others only have a small though important part of the ancient ecclesiology.
Regardless of these distinctions, and their importance as a barrier to unity among all Christians, I still pray after the example of Christ and Pope John Paul II that we may all be one.
By User:Julian Mendez - User:Julian Mendez, Public Domain, https://commons.wikimedia.org/w/index.php?curid=2547972