Sin is often the result of lust or wrong selfish desire. This fact forms the primary basis of answering this question. Jesus tells us in Matthew 5:28 that “whoever looks at a woman to lust for her has already committed adultery with her in his heart.” Sexual lusting in the mind is the primary reason or trigger for masturbation and is sin—whether from erotic imagery, viewing pornography, or lusting after a person who is not one’s spouse. A Christian must therefore learn to control his thoughts (2 Corinthians 10:5).
As the apostle James wrote: “But each one is tempted when he is carried away and enticed by his own lust. Then when lust has conceived, it gives birth to sin” (James 1:14-15, New American Standard Bible).
The Bible specifically forbids adultery, fornication, homosexual sex, incest, bestiality and lust but does not mention masturbation or self-stimulation. Masturbation as part of sexual relations between married partners would not be classified as sin. But masturbation outside of marital relations commonly is sinful, being often accompanied by wrong lustful thoughts, such as when viewing pornography.
The use of pornography (including so called “soft porn”) is definitely a sin, as it violates Christ’s teaching in Matthew 5:28. Looking lustfully at risqué entertainment and immoral fantasizing are all clearly sinful. Addictions to porn and masturbation will reinforce each other. When a person stops viewing or thinking about anything wrongly erotic, there won’t be so much improper sexual arousal with urges to masturbate.
The Bible does not teach asceticism, such as the pagan Gnostic teaching that all physical things are evil, including the human body. God designed human beings with sexuality—“male and female” (Genesis 1:27; Matthew 19:4)—for many reasons, but especially so they can marry, enjoy marital love, have children and enjoy many other blessings. Marriage is sacred and critically important to God. Therefore, one must not allow anything to hinder the success of his or her present marriage or a future marriage.
Lustful self-stimulation can easily become a habit that hurts a marital relationship and future sexual satisfaction with one’s spouse. A habit formed before marriage can be difficult to break even after getting married. Many marriages have been seriously hurt because one or both of the spouses had a secret habit of masturbation. (The United Church of God offers a valuable free study guide on love, sex and marriage—Marriage and Family: The Missing Dimension.)
Because sex is powerful, masturbation can also become an addiction. Any addiction is spiritually dangerous because it has become the master, and the addict has become the slave—and we must only be “slaves of God” (Romans 6:22). Remember that it is easier to prevent a habit or addiction than to break an already-formed habit or addiction.
As Christians, we are to be “bringing every thought into captivity to the obedience of Christ” (2 Corinthians 10:5). This of course requires His help. We must constantly be asking God to renew and strengthen us. The practical method for stopping unwanted thoughts is to replace them with good thoughts (Philippians 4:6-8). Strive with God’s help for spiritual growth in all areas of life and, as a result, you will become stronger in those areas where you have been the weakest.
Once God has called us to be His disciples, we are doubly responsible to Him for how we use our time, our minds and our bodies. We are called to bear “good fruit” and “much fruit” spiritually (Matthew 7:15-20; John 15:1-8). And part of the fruit of God’s Spirit is self-control (Galatians 5:22-23). Don’t allow anything habit-forming or lustful to interfere with these goals.
Make sure to pray to God and read His Word every day to discern His will in your life. In that way, you are regularly talking to God and listening as He speaks to you. We encourage you to read our free study guide Tools for Spiritual Growth. It thoroughly explains prayer, Bible study, fasting, meditation and three other “tools” that are essential for spiritual growth. We highly recommend it!