In the Bible, spiritual fornication is equivalent to idolatry. This is where a person who was supposed to be worshiping the true living God, is serving false gods, i.e., Mormonism, Jehovah’s witnesses, and Catholicism when it comes to Mary.  It is referred to as playing the harlot (Judges 2:17; 8:27, 33; 1 Chronicles 5:25).  the term is used in reference to Israel in the Old Testament because though Israel had been called by the true and living God, they would sometimes worship false gods such as Baal (1 Kings 18:26–29), “other gods” (Joshua 24:2), household idols (Genesis 31:34), golden calves (1 Kings 12:28), etc.

God expressly forbids idolatry. “You shall not make for yourself an idol, or any likeness of what is in heaven above or on the earth beneath or in the water under the earth,” (Exodus 20:4). yet, people would turn to those things which they believed they could manipulate in order to satisfy their desires. The God of Scripture is not a butler who desperately seeks the fellowship and acceptance of his subjects. Instead, God is sovereign and our prayers and our desires should be in accordance with his will. If things don’t go the way we want them to as quickly as he wants them to, we should not turn to other things such as false gods, pornography, drugs, get-rich schemes, etc.

• “But I have a few things against you because you have there some who hold the teaching of Balaam, who kept teaching Balak to put a stumbling block before the sons of Israel, to eat things sacrificed to idols and to commit acts of immorality,” (Revelation 2:14).
• “But I have this against you, that you tolerate the woman Jezebel, who calls herself a prophetess, and she teaches and leads My bond-servants astray so that they commit acts of immorality and eat things sacrificed to idols,” (Revelation 2:20).

Conclusion on spiritual fornication

Spiritual fornication, idolatry, can take many forms. We must be careful not to look down at the ignorant and ancient pagans and faulty Israelites who worshiped at the foot of wooden idols and think that we are superior to them in intellect and knowledge. Idolatry is that which places something above the sovereignty, majesty, adoration, and dependence of the true and living God. We can fall into varying forms of spiritual fornication, spiritual idolatry, even as Christians by depending on money, cars, looks, or whatever else might supplant God’s true place in our lives.