Note 14 at 1Co 6:18: We are told to resist the devil (Jas 4:7) because fleeing from him is neither wise nor possible. As long as we are in this life, we will come in contact with Satan and/or his imps, and we need to stand our ground and fight. He will flee from us.

However, sin and the temptation to sin are things we can avoid. We are not instructed to resist fornication. We are told to flee fornication.

The American Heritage Dictionary defines "flee" as "1. To run away, as from trouble or danger. 2. To pass swiftly away; vanish." In every sense of the word, it means a removal from a person or thing. Therefore, this command to flee fornication is a command not just to refrain from the physical act but also to remove ourselves from the temptation.

Many Christians "flirt" with fornication, as well as other sins, never intending to commit the physical acts. They are sure they can resist the actual sin, but that is not the way it works. Sin is easier to avoid than it is to resist.

Note 15 at 1Co 6:18: Paul mentioned in Ro 1:27 that homosexuals received in their bodies a just payment for their sin. This probably refers to the many sexually transmitted diseases that can be contracted from such behavior. Likewise here, Paul was saying that sins of sexual immorality are the only sins that hurt our bodies. This must be understood in a comparative sense because many sins (gluttony, drunkenness, etc.) are physically damaging.

In some special way, sexual immorality gives place to the devil against our physical bodies. Therefore, it would be logical to assume that many physical problems have their entrance through sexual sins.