Why do believers still fall into sin when they struggle?
Believers still fall into sin because when the spirit part withdraws from the battle line, old Adam takes the opportunity and begins to control the acts of the body. The two natures are contrary, so they cannot do what they would. Yet exercising the spirit through the Word, prayer, and Christian fellowship helps control the body's activity.
Les explains that we all fail and fall. When the spirit part of us suddenly withdraws from the battle line, old Adam immediately jumps at the opportunity and begins to control the acts of the body, so believers naturally sin. Les emphasizes that believers do sin and cannot get away from that. But the whole idea is to keep that spirit part literally exercised by the Word, by prayer, by Christian fellowship, and then we can pretty much control the activity of the body. Even though the two natures are contrary one to the other, so we cannot do the things we would, if we are led of the Spirit, then we are not under the Law. Les points to the Apostle Paul’s dilemma in Romans 7 as comfort, showing we are not alone when we know we should do something and do not, or know we should not do certain things but do them anyway. He directs us to Romans 7:15.