Genesis 4:7 New International Version (NIV)
7 If you do what is right, will you not be accepted? But if you do not do what is right, sin is crouching at your door; it desires to have you, but you must rule over it.”
In order for Cain to control and put down the sin that was waiting to attack him and to cause destruction in his life, he would have had to give up his jealous anger toward Abel. If he had not let it take a foot hold, the sin would not have been embedded into his life. Sin is always wanting to attack us and destroy us. You will be a victim of sin if you do not learn how to master it. You cannot master sin with your own strength. You may be able to do it for a time, but you will weaken and cave in. You need the strength of God and his Word. You must turn to God to receive faith for yourself, as well as, encouragement and strength. Do you think you can master sin just like that? No! It takes work, many tries, and fighting through the failures. Do not let the failures beat you. Learn from them. Walk with God. Get stronger and stronger. The Holy Spirit will help you. Jesus is your petitioner. This is a lifelong battle we all face, but having God with you, the Holy Spirit as your helper, and Jesus as your Lord; you can win the war.