Answer
A fantasy is an act or event created in the imagination; in most cases the imagined act is impossible or improbable. A sexual fantasy creates a sexual act or event in the imagination. Depending upon the nature of the fantasy and the imagined players in it, a sexual fantasy can be a sin. Any imagined scenario that is inappropriate for moral, ethical, or spiritual reasons is sinful.
Imagination is a gift from God, and fantasy is part of the human psyche. We fantasize often without even realizing it. Fantasies can range from imagining that we hit all green lights on the way to work and arrived early, to conjuring up vile and physically impossible acts. Fantasies are usually spawned from our personal reality and are attempts to create a reality we prefer rather than the one that exists. Some people become so wrapped up in their fantasy life that they disconnect from reality and real relationships. Some internet options allow people to create virtual characters and live vicariously through those characters. Sexual fantasy is often a part of that virtual reality and allows people to simulate sexual acts without actually being physically present.
Proverbs 23:7 says that whatever we think in our hearts, that is who we are. Many would argue, “But I’m not actually doing anything wrong.” However, the Bible speaks a lot about our thoughts and is clear that even our fantasies are to be brought into submission to God’s will. Jesus said, “But the things that come out of a person’s mouth come from the heart, and these defile them. For out of the heart come evil thoughts—murder, adultery, sexual immorality, theft, false testimony, slander” (Matthew 15:19). He also said that even looking upon someone with lust is as the sin of adultery (Matthew 5:28). If the sexual fantasy consists of actions or words that are not in line with God’s will for us, then it is sin. Sexual fantasies about our marriage partners may not be sin, if we are morally free to act upon those fantasies. But if we are imagining engaging in sexual acts with someone to whom we are not married, it is lust. And lust is sin.
We cannot always control the thoughts that shoot through our minds. We are exposed to sexual stimuli continually, and it can be difficult to process these stimuli in God-honoring ways. Ephesians 6:16 talks about the “fiery darts of the wicked one.” Our minds are Satan’s target for those darts, and sexual fantasies are one of the fiery darts that, left unchallenged, can lead us into sin. James 1:13–15 shows us the progression of sin, beginning with an “evil desire.”
When evil desires arise in our hearts, we have a choice about what we do with them. We can entertain them, allowing them to erupt into full-blown fantasies, or we can “take every thought captive to the obedience of Christ” (2 Corinthians 10:5). As Christians, we have the power of the Holy Spirit working in our lives to enable us to squelch the beginning of an ungodly fantasy. When we realize we are daydreaming about something that God has said is off-limits, we can quickly arrest that thought, confess it to Jesus, and ask His forgiveness (1 John 1:9).
At a later time, it may be helpful to scrutinize the kind of fantasy that seems to dominate your thoughts. Fantasies often reveal unmet needs that God wants to supply in healthy ways. Likewise, sexual fantasies can showcase a wounded place in our spirits that God needs to heal. If the fantasies persist and are disturbing, seeking godly counsel can help uncover the root of the heart wound producing them. When in doubt about a sexual fantasy or any other consuming thought, we can always apply the Philippians 4:8 test to see if it is pleasing to God. He wants to be Lord of every part of us, including our fantasies.
