For a thousand years, in most of Europe, every person was a Christian. Baptized at birth. Registered in the parish. Married, buried, and taxed by the church. To be born was to be a Christian, and the alternative wasn't unbelief but exile.
It sounds like triumph. It was the emptying of a word.
Top-down conversion
The conversion of Europe happened, for the most part, by ruler. When a king was baptized, his people were baptized. Charlemagne's law for the conquered Saxons made refusal of baptism a capital offense; Alcuin, the most learned man at his court, objected in writing that faith can't be compelled and that baptism without belief is a washing without cleansing. He was right and he was ignored.
Then the principle was stated as law in the sixteenth century: cuius regio, eius religio — whose the realm, his the religion. The ruler's faith was the territory's faith. Christianity had become a property of geography.
Jesus had said something different:
Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven. Many will say to me in that day, Lord, Lord, have we not prophesied in thy name?... And then will I profess unto them, I never knew you. (Matthew 7:21-23)
Not every one that saith. The name isn't the thing. And a system that assigns the name to everyone at birth has guaranteed that the name and the thing will come apart at the scale of a continent.
Baptism as civic registration
Under Christendom, baptism kept its meaning as a sacrament and acquired a second function: it was how a person entered civil society. The parish register was the birth certificate. To be unbaptized was to be legally nonexistent.
This isn't a claim about the validity of infant baptism, which is a separate question. It's a claim about function. When the same act that marks entry into the church also marks entry into the state, the act can't distinguish the two, and the church has no way of knowing who among its members is a believer. Everyone is registered. Nobody has been asked.
And the thing that had done the asking — the catechumenate, the years of instruction and sponsorship and public renunciation before baptism — collapsed. There was no one left to catechize. Everyone was already in.
The word that describes nothing
This is the consequence, and it's a logical one before it's a spiritual one.
A word means something by distinguishing. "Tall" means something because some people aren't tall. "Christian" in the New Testament meant something because most people weren't: the disciples were called Christians first in Antioch (Acts 11:26) — a name given to a visible minority whose lives marked them off. Peter can say if any man suffer as a Christian, let him not be ashamed (1 Peter 4:16) because being one was a distinguishable and costly condition.
When everyone is a Christian, the word distinguishes nothing. It describes a population, not a people. And a congregation that's simply the population of a district has no way of telling its wheat from its tares, because the tares were sown at birth and registered in the same book.
Jesus's parable of the tares presupposes that the two will be mixed and will be sorted at the end (Matthew 13:24-30). Christendom didn't merely mix them. It made the mixing total and official, and removed every mechanism by which the mixture could be seen.
Assurance anxiety as a structural product
Look at what happened to the individual believer inside that system.
If everyone is a Christian by birth, and Jesus has said that not everyone who says Lord, Lord will enter — then the question am I really one? becomes unanswerable by any external sign. Membership means nothing; everyone has it. Baptism means nothing distinctive; everyone had it. Attendance means nothing; it was compulsory. There's no visible community of the committed to belong to, because the community is the whole town.
So the question turned inward. The medieval and post-Reformation obsession with assurance — am I elect, am I truly converted, is my faith real — is usually treated as a spiritual phenomenon. It's also a structural one. It's exactly the anxiety a person would feel when every outward marker of belonging has been assigned to everyone, and the only remaining evidence is internal, and the internal evidence is by nature uncertain.
The New Testament had answered the question differently. We know that we have passed from death unto life, because we love the brethren (1 John 3:14). By this shall all men know that ye are my disciples, if ye have love one to another (John 13:35). The evidence was relational and visible: you were a Christian because you were among Christians, doing what Christians do, in a community that could see it. Christendom removed the community — by making it universal — and left the individual alone with his doubts.
The parish: right geography, wrong voluntarism
Two columns, always. Christendom got something right that the modern church has lost: geography. The parish was a place. Everyone within its boundaries belonged to the same church, lived near each other, and couldn't commute away from one another. Care was local; the poor of the parish were the parish's responsibility; the church was present in every village.
What it got wrong was voluntarism. Nobody chose. The New Testament church was a voluntary association of people who had heard, believed, renounced, and joined — they that gladly received his word were baptized (Acts 2:41). Christendom had the right geography and removed the choice; the modern church has restored the choice and lost the geography. Neither is the design. The design is both: a chosen community, present in a place.
Church as country
When the church became coextensive with the nation, three things followed.
First, the church's enemies became the nation's enemies, and the nation's wars became holy. Second, dissent from the church became treason, and the church acquired an interest in the state's coercive power that Jesus had explicitly forbidden — so shall it not be among you (Mark 10:43). Third, and most quietly, the church lost the ability to be sent. You can't go to the nations when you're the nation. Mission became something that happened at the edges of Christendom, to pagans, rather than the ordinary condition of every household.
The renewal movements of the Middle Ages — the friars, the lay brotherhoods, the confraternities, the later pietist circles — were antibodies. Every one of them was an attempt to recover a chosen community inside the unchosen one, an ecclesiola in ecclesia, a little church within the church, where the name could mean something again.
What Paul predicted
Paul told Timothy what the end-state of a formally religious population would look like:
Having a form of godliness, but denying the power thereof: from such turn away. (2 Timothy 3:5)
A form of godliness. The word is morphosis — the outward shape, the appearance. A population that has the form and not the power is exactly what universal profession produces. And Titus 1:16 names the mechanism: They profess that they know God; but in works they deny him. Profession universal, works absent, and no community in which the gap could be seen.
The Lord of the churches said it to Sardis: thou hast a name that thou livest, and art dead (Revelation 3:1). A name. That's what Christendom distributed to everyone — and a name that everyone has isn't a name anymore.
What to recover
Not persecution, and not a smaller word for its own sake. The recovery is of the two things Christendom separated: the choice and the place.
A congregation in which membership means something — in which people have heard, believed, and joined, and in which the joining involves renouncing something at the door — has a word that distinguishes. A congregation that is present in a place, so that its members live near each other and can't commute away from one another's burdens, has the parish's one virtue back.
And a believer inside such a community has what Christendom took away: visible evidence. We know that we have passed from death unto life, because we love the brethren. Not a feeling. A fact about a room full of people who can see it.