When temptation enters our hearts and minds, we either deal with it and gain mastery over it, or it eventually leads us to sinful actions. The time between the initial temptation and the chosen response is critical. Much hangs in the balance.
Cain knew that God was displeased with him but pleased with Abel. Feelings of jealous anger crept into Cain's heart, and thoughts of murder pervaded his mind. As Cain considered what to do, God's Word came to him. God warned him that sin was waiting at the door of his life, looking for an opportunity to enter. Now was not the time to treat temptation lightly, not the time to assume sin would never cause any harm. Now was the time to master the sin and renounce it before it overcame him. Tragically, Cain did not master his sin; instead, sin overtook him and destroyed his life.
Sin is still waiting to attack and destroy us today. Temptations come at unexpected moments. Sinful thoughts may cross your mind. Selfish feelings may begin to invade your heart. The promptings of the Holy Spirit will warn you that God is not pleased with the direction your thoughts and feelings are taking you. At that moment of conviction, you must master the sin that crouches at the door of your life. Sin destroys. Sin brings death. Sin is not something to toy with or take lightly. God's Word to you is the same warning He gave to Cain: Master the sin at the door of your life before it brings its inevitable and disastrous consequences. Heed His caution, and you will avoid unnecessary hardship for yourself and others. But we cannot master sin in our own strength. Instead, we must turn to God to receive faith for ourselves and turn to other believers to receive encouragement and strength. The Holy Spirit will help us master sin. This will be a lifelong battle that will not be over until we are face to face with Christ.
"The Bible Knowledge Commentary" by John F. Walvoord and Roy B. Zuck