A popular story says the first Christians cared about justice and that rules about private sexual conduct, the sin the King James Bible calls fornication, came later. On this account, the shift happened in the fourth century, after Constantine and once the church had the empire’s favor. The sources say otherwise. A personal sexual ethic is already present in the Jewish world Jesus was born into, in his own teaching, in Paul’s letters, and in Christian writing from the centuries when the faith was illegal. Constantine arrives at the end of that sequence, not at its start.
This guide does not try to settle whether Christians should live by that ethic. Its paired article takes up that question. This guide tests a historical claim, and a historical claim always contains a date. The work here is to build the chronology yourself, station by station, and ask at each point what people could have known and what later readers have projected backward. You can work through it alone in about an hour. A group can cover it in one long session or split it across two, with the timeline practice as the hinge between them.
The claim has a date in it
Start by stating the claim precisely, because vague versions cannot be tested. The strong version runs like this. Before Constantine, Christians focused on challenging unjust power. After Christianity became the religion of the empire, leaders turned believers’ attention toward personal piety, including sexual sin, so they would stop challenging the powerful. Lisa Fields laid out this argument in her conversation with Dr. Esau McCaulley, a New Testament scholar at Wheaton College, so he could respond to it.
Notice what that version commits to. It predicts a before and an after. If it is true, the “before” side of the timeline should be thin or silent on personal sexual holiness, and the “after” side should be where the ethic first appears. So the test is simple to describe. Go to the earliest material and look.
McCaulley proposes exactly that order of inquiry. “You can look at the surrounding culture, the surrounding Jewish culture out of which Jesus and Paul arose,” he says, and from there move to Jesus, to Paul, and to the church writers of the first three centuries. The sections below follow that sequence.
Station one: the Jewish world before and around Jesus
The first question is what a Jewish teacher in Galilee could assume his listeners already believed. McCaulley argues that fidelity in marriage was not a live controversy in Jesus’ day. His evidence is the shape of the arguments Jesus actually had: “when Jesus and the Pharisees are having a fight, they never fight about the particular aspects of sexual morality.” They argue about other things. Sexual fidelity sits in the background as shared ground.
McCaulley also points to a group outside Jesus’ circle: the community at Qumran associated with the Dead Sea Scrolls. When Lisa asked him to clarify, he explained that he meant the people who wrote the scrolls, a separatist community living in the wilderness at the same time as Jesus. “They’re out there in the woods and they’ve outlawed polygamy,” he says, and he describes their ethic as basically traditional. He also tells listeners not to treat the matter as a conspiracy theory: “There’s actual data,” and anyone can look it up.
Keep a careful line here between what McCaulley asserts and what you have read. This guide does not reproduce the Qumran texts. On your timeline, his description belongs in the column for a scholar’s summary until you check the scrolls or a reliable edition of them yourself. That is not distrust. It is the same discipline he recommends.
Against that background, read what Jesus does with the inherited standard. “But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart” (Matthew 5:28). McCaulley reads this as movement upward from the shared Jewish ethic, describing it as “a raising of the moral stakes.” Then read Matthew 15:19: “For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies.” Adultery and fornication stand as separate items. McCaulley’s point is that Jesus knew a category of sexual sin that did not involve taking someone else’s spouse.
Why does Jesus say less on this than Paul? McCaulley’s answer is about audience. “Jesus never leaves the boundaries of Israel,” so he can build on what his hearers already hold. Silence on a point everyone accepts is not the same as indifference to it.
Station two: Paul in the cities of the Greek and Roman world
The scene changes when the message reaches Gentiles who never shared that Jewish consensus. “Paul has to build the ethics up,” McCaulley says. That is why Paul writes plainly where Jesus did not need to.
Read two short passages from Paul with the timeline in mind. “For this is the will of God, even your sanctification, that ye should abstain from fornication” (1 Thessalonians 4:3). And from 1 Corinthians 7:2: “Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband.” Two verses later comes a line McCaulley stresses: “The wife hath not power of her own body, but the husband: and likewise also the husband hath not power of his own body, but the wife” (1 Corinthians 7:4). He notes that the first half would not have surprised anyone in a culture that assumed male authority. Telling a grown man his body belongs to his wife was the change.
This station also tests the motive the story assigns. If the ethic was designed to serve the powerful, it should have cost the powerful nothing. McCaulley argues the opposite. Wealthy Roman men had sexual access to slaves and to poor women and boys, and Paul told them to stop. “Paul’s sexual ethic was actually counter imperial,” he says. The claim that this teaching was a way of courting Rome, in his words, “doesn’t understand how imperial politics work.”
Place one more item at this station. When the apostles in Jerusalem wrote to Gentile believers, their letter asked them to abstain “from meats offered to idols, and from blood, and from things strangled, and from fornication” (Acts 15:29). This is a leadership decision recorded in Scripture, centuries before any emperor took an interest in the church, and fornication is on its short list.
Station three: the centuries of persecution
This is the stretch the story says should be quiet. McCaulley names writers from it and issues a challenge: “read Ignatius, read Polycarp, read Justin Martyr.” Elsewhere in the conversation he puts it more bluntly: “I dare you to read the church fathers pre Constantine.” His own report of what you will find is that “you can find in those first three centuries Christians talking about personal holiness over and over and over and over again.”
He adds an argument from consequences. He describes bishops arriving at the Council of Nicaea “having arms cut off and eyes missing,” and he asks: “Why would they persecuted them for 300 years if they would just say what the empire wanted them to hear?” He also mentions “Athanasius who got exiled five times.” These are McCaulley’s historical claims, and on your timeline they belong in his column until you verify them. The reasoning, though, does not rest on any single detail. A movement the empire kept punishing makes a poor candidate for a movement shaped to please it.
McCaulley also describes early Christian women who chose not to marry and devoted themselves to the Lord, and he says those around them saw a single woman living on her own terms as a threat to stability. Again, this is his summary. If it holds, it is another sign that Christian sexual teaching unsettled the social order rather than propping it up.
A parallel track: rabbinic Judaism
One witness does not fit neatly on the same line, and it is worth seeing why. McCaulley argues that after Judaism and Christianity went separate ways, “the basic sexual ethic that you see in early rabbinic Judaism is pretty close to what you see in the New Testament.” The rabbis never had Constantine’s favor and had no reason to flatter a Christian emperor.
Draw this as a second line running beside the Christian one, not as an earlier point on the same line. The evidence here works by independence, not priority. Its force is that a community with no imperial patron, reading the same Hebrew Scriptures, arrived at a similar ethic. That is a different kind of evidence from Qumran, which works by being contemporary with Jesus. Telling these two apart is part of reading history well.
After the turn: Constantine, Augustine and reading backward
In the conversation, Lisa Fields recalled that Augustine placed heavy emphasis on overcoming sexual sin. That is a fair observation, and it shows exactly how the story can form. Augustine wrote after Constantine. If a reader meets the ethic first in a later, famous writer, it is easy to assume that is where it began.
Chronology corrects the assumption. A later writer’s emphasis tells you what that writer stressed. It cannot tell you that the idea was absent before him. To answer an origin question, you need the earliest evidence, and the stations above come first. This is the general error the guide is training you to catch: treating a later institution’s actions as the explanation for a belief that was already there.
McCaulley also challenges a split the story takes for granted. “The Bible is actually sophisticated enough to say two things at the exact same time,” he says, and he calls it “a modern distortion to say that because you care about structural injustice, there is no such thing as personal holiness.” The paired article develops this point through Isaiah and Jesus. For your timeline, the takeaway is narrower. At no station do you find justice-only Christianity followed by holiness-only Christianity. Both concerns appear together from the beginning.
The practice: build the timeline yourself
This exercise turns the material above into something you have checked rather than something you were told. Give it thirty to forty minutes. In a group, split the stations among pairs and then assemble the full line together.
- Draw a horizontal line on a sheet of paper. Mark four regions: the Jewish world around Jesus, the apostolic writings, the centuries of persecution, and after Constantine. Draw a second, shorter line beneath for rabbinic Judaism.
- Place each item from this guide on the line: Qumran, Matthew 5:28, Matthew 15:19, 1 Thessalonians 4:3, 1 Corinthians 7, Acts 15:29, the persecution-era writers, Nicaea, Athanasius, Augustine.
- Beside each item, write one of three labels. Text I read means you looked at the passage itself. Scholar’s summary means you are relying on McCaulley’s description. Inference means a conclusion drawn from the evidence, such as the argument from persecution.
- Pick one item labeled Scholar’s summary and try to move it to Text I read. The simplest choice is a short letter by Ignatius or a chapter from Justin Martyr in any public-domain translation. Write down one sentence the writer actually says about personal conduct, and note whether it confirms, complicates or fails to address McCaulley’s claim.
- Look at the whole line and ask the question the story requires: where does the personal sexual ethic first appear? Then ask a second question: which of your items, if it turned out to be wrong, would change that answer?
The last step matters most. A strong case is one that survives the loss of a single piece. If you find that removing Athanasius or the Nicaea report changes nothing, because Matthew 15:19 and Acts 15:29 already settle the origin question, you have understood how the evidence is weighted.
Questions for discussion
- The story under examination makes a claim about timing. Why do you think a claim like this can spread without anyone checking the dates?
- Qumran and rabbinic Judaism support McCaulley’s case in different ways, one by being contemporary with Jesus and the other by being independent of the empire. Which kind of evidence do you find more persuasive, and why?
- McCaulley explains Jesus’ relative silence on some sexual questions by pointing to his audience. Is an argument from audience a strong one? What would make it weaker?
- When you placed items on your timeline, which ones did you have to label as a scholar’s summary? How confident should a person be in a conclusion that rests partly on summaries they have not checked?
- Lisa Fields says, “you don’t combat the misuse of scripture by misusing it.” How does that principle apply to the way people have sometimes told church history, on either side of this question?
- McCaulley says of the traditional ethic, “I actually believe it because I think it’s what the text says.” What is the difference between holding a belief because you have tested the sources and holding it because your community does?
For those leading a group
Keep the session on the historical question. Some participants will want to argue whether the ethic is right. Note that the paired article addresses that question, and bring the group back to dates and documents.
Be aware of who may be in the room. Lisa Fields points out that people who were sexually abused as children can hear teaching on purity as an accusation, because the choice was taken from them. McCaulley warns that a preacher can win applause on this subject without noticing someone trapped in an abusive marriage or someone carrying sexual sin. Nobody should be asked to share personal history in this study, and the timeline exercise is designed so that no one has to. If a participant is in an abusive relationship, their safety comes first, and the National Domestic Violence Hotline is available at 1-800-799-7233.
If the group has time for only one activity, choose step 4 of the practice. Reading a few paragraphs of a second-century Christian writer together does more than any summary to show what the persecuted church actually talked about.
A question to carry
The next time someone tells you a Christian belief was invented at a certain moment for a certain motive, ask for the earliest evidence and look at what sits on the timeline before that moment. For this claim, the answer is already in Matthew 15:19 and Acts 15:29, written long before any emperor took an interest. Whatever a person decides about Christian sexual ethics, the decision concerns the teaching of Jesus and his first followers, not a fourth-century political move.