What sexual acts are sinful, even in marriage?

Last updated on August 20, 2020


Besides anal sex, are there any other sinful sexual acts in a marriage? If so, what are they?


The Bible uses or refers to numerous sexual acts. Any sexual act that takes place between two people who are not married is called fornication and is forbidden (I Corinthians 6:9-10; Hebrews 13:4). Under this broad category are several more specific terms:

  • Adultery is where at least one of the people is married but is having sex with someone to whom they are not married. This also is a sin.
  • Incest is when a person has sex with a close relative. Whether they were technically married or not, such a relationship is forbidden (I Corinthians 5:1).
  • Homosexuality is when two people of the same gender are having sex. This is forbidden (I Corinthians 6:9-10). Even though the United States is rapidly permitting “marriages” of two men or two women, it remains a sin.
  • Bestiality is when a person has sex with an animal. That is forbidden.
  • Polygamy is when a person is married to more than one person at the same time. This is forbidden in Matthew 19 by implication that marriage is for a man and a woman.
  • Prostitution is when a person sells their body for sex. It is wrong for both the prostitute and the one purchasing the service.

Even when a man and woman are married properly, some acts of sex are wrong because they cause harm to another person.

  • Forced sex: Even though sex is expected within marriage and both partners are supposed to be available for the sexual needs of their partner when a partner is unwilling at that time, the other partner does not have the right to force sex to take place anyway. That is not being kind to the other person, so it is not love. Forced sex can also cause physical harm, which again is not what love is about.
  • Embarrassing or public sex: Sex is to be an intimate act between a married couple. It is wrong to make it a spectacle in front of other people. Sadly we have people recording their sexual acts and making them available on the Internet as pornography. Such should not be. Love is not rude and does not act unbecomingly.
  • Sadomasochism: Some people find it sexually stimulating to hurt or be hurt. There are physical mechanisms that explain why this happens, but the fact remains that harm is being done. You find people in the name of sex spanking, punching, scratching, and even choking in order to get a sexual thrill. That is not love, for love doesn’t cause harm.
  • Anal sex: This is where a man puts his penis into the rectum of another. It is more common among male homosexuals, but you find it creeping into marriages. The problem is that it causes harm to the people engaged in it, even when they attempt to be careful. Therefore it is also wrong.
  • Pornography: Young men frequently get trapped by this sin of looking at nude pictures and pictures of people in sexual acts. Men tend to be visually stimulated and the site of other people sexually aroused causes them to become sexually excited as well. In the Bible, this sin is usually referred to as sensuality. Even in marriage couples should not be using images of people to whom they are not married to sexually stimulate themselves.