Weird Things That Early Christianity Regarded As Sexual Sins

Early Christian beliefs about sex might not seem surprising at first: intercourse was generally seen as evil, and it was only acceptable after marriage. But dig a little deeper into the rules for early Christianity, and you’ll find all kinds of weird stuff.

When it came to Christianity and premarital intimacy, the rules were strict—and sometimes they were just as strict once you were married. Doing it on the wrong day or in the wrong position made even marital intercourse a sin, according to early Christianity.

Medieval Christianity wasn’t as buttoned-up as some people believe. And some things haven’t changed much since the Middle Ages. As for adultery in the Middle Ages, who knew that sleeping with your wife could be adulterous? And that’s only the beginning—wait until you see what early Christians called “the worst evil.”

  • Wisdom Held That 'It [Was] Better To Marry Than To Be Burnt'
    Photo: Unknown / Wikimedia Commons / Public Domain

    Wisdom Held That 'It [Was] Better To Marry Than To Be Burnt'

    Certain sexual sins in early Christianity were pretty straightforward: no intercourse before marriage. No inter-familial relationships. No rape. And definitely not whatever’s happening in this 14th-century manuscript.

    But other sexual sins are pretty weird by modern standards. Many of them boil down to one principle, enshrined in early Christianity: intercourse and lust were polluting, and they should be avoided if at all possible. Saint Paul recommended celibacy, but he agreed that those who could not "contain themselves" should find a spouse, "for it is better to marry than to be burnt." That's right: lust sent you straight to Hell.

    If you just had to do it, it could only occur under very specific conditions. And any kind of intercourse that could not lead to procreation was a sin.

  • Abstinence On Sundays—Or Thursdays, Fridays, Christmas, Or Feast Days
    Photo: Meister des Codex Manesse / Wikimedia Commons / Public Domain

    Abstinence On Sundays—Or Thursdays, Fridays, Christmas, Or Feast Days

    The early Christian church went out of its way to limit intercourse—even between married couples. Religious laws and proclamations issued by the Catholic Church tried to restrict when people could sleep with each other, and they ended up banning most of the year. No "happy time" on Sundays, one rule proclaimed. That was the Lord’s Day, and it shouldn’t be contaminated by lust. And don’t plan on doing it on Thursdays or Fridays, either, because those days should be spent preparing for communion.

    Intercourse was also banned during Lent, before Christmas, and at the Feast of Pentecost, which together added over five months during which it was disallowed. On top of that, early Christians were not supposed to have relations on Feast Days. In the early church, you pretty much had to check your calendar before getting it on.

  • Don't Be Tempted By Thighs – They're Sinful, Too
    Photo: Andrea Mantegna / Wikimedia Commons / Public Domain

    Don't Be Tempted By Thighs – They're Sinful, Too

    Never heard of intercrural intercourse? Don’t worry, it’s a sin according to early Christians. Intercrural intercourse was “copulation between the thighs.” This sort of thigh rubbing to completion was an “act against nature,” according to the church—even if it occurred between husband and wife. But intercrural intercourse was more often associated with same-gender practices, which the church found problematic because they could not lead to conception.

    Thomas Aquinas labeled all sexual activity besides vaginal intercourse “sodomy,” regardless of the gender of the people involved, because those sexual acts could not cause pregnancy.

  • Even Thinking About Doing It Was A Sin
    Photo: Henry Holiday / Wikimedia Commons / Public Domain

    Even Thinking About Doing It Was A Sin

    Even thinking about bumping uglies was a sin according to the early Christian church. Anselm of Canterbury, an 11th-century monk, put it this way:

    There is one evil, an evil above all other evil, that I am aware is always with me, that grievously and piteously lacerates and afflicts my soul. It was with me from the cradle, it grew with me in childhood, in adolescences, in my youth it always struck me, and it does not desert me even now that my limbs are failing because of my old age. This evil is sexual desire.

    Anselm described it as “the storm of lust that has smashed and battered my unhappy soul, emptied it of all strength, and left it weak and empty.” So yes, even thoughts could be sexual sins to early Christians.

  • Bestiality Was Really Bad If You Had A Wife, But Not Terrible If You Were Single
    Photo: Getty Center / Wikimedia Commons / Public Domain

    Bestiality Was Really Bad If You Had A Wife, But Not Terrible If You Were Single

    Generally, most societies frown on bestiality. Early Christianity is no exception, but the church made a major distinction in its punishments for bestiality. One medieval Penitential, a guide book for priests to give punishments for sins, made this clear. “Have you fornicated against nature... with a mare or a cow or a donkey?” If the man answered yes, the priest was supposed to find out if the man had a wife or not. “If once or twice and if you had no wife to enable you to expend your lust, you must do penance for 40 days. If, however, you had a wife, you must do penance for 10 years.”

    The point was that married people were supposed to use their spouse to get rid of lustful urges. But essentially, the church said bestiality wasn’t so bad if you were unmarried. 

  • Sleeping With A Pregnant Woman Was A Sin—And Pointless
    Photo: Wellcome Images / Wikimedia Commons / CC-BY-4.0

    Sleeping With A Pregnant Woman Was A Sin—And Pointless

    The early Christian church argued that intercourse existed for one purpose—procreation. That idea shaped many of the rules about intercourse. One of those was the ban on sleeping with pregnant women. The church said it was unnecessary once a woman was pregnant—she couldn’t exactly get pregnant again. And beyond that, early Christians believed that doing it during pregnancy could cause spontaneous abortions or birth defects. According to a medical text that was popular during the early church, the fetus might be "defective in vital and other qualities, ill tempered, sickly, and short-lived” if the parents slept with each other during pregnancy.