There is sin of commission (doing what you should not be doing) and sin of omission (not doing what you should be doing). Every event of sin is produced from the flesh; sin living within us is the power of satan.
After the Gospel is preached and understood (on good soil) the proper response is to repent and believe in God. Repentance is the act of not doing what should not be done in the first place; believing in God is the act of doing what should be done (our faith produces in us good works).
This is why our repentance cannot earn us eternal life, because we should not have been doing those things that should not have been done in the first place. How can God reward us for not doing what we shouldn't have done to begin with?
If we stop doing the things we know we shouldn't be doing but fail to start doing the things we know we should be doing, we will inevitably once again start doing the things we know we shouldn't be doing. This is why it is necessary to repent and believe, instead of just repentance. If we fail to turn to the living God in faith, we will slide back into what we've known from the beginning.
Although, we all have the power of sin living within us, which is the power of the devil, we who believe also have another power living within us which is much more powerful than that of the devil: the power of God through the Holy Spirit. Our mind is the battle field where these two powers fight.
"The sinful nature wants to do evil, which is just the opposite of what the Spirit wants. And the Spirit gives us desires that are the opposite of what the sinful nature desires. These two forces are constantly fighting each other, so you are not free to carry out your good intentions." (Galatians 5)
"If you live by its (the flesh) dictates, you will die. But if through the power of the Spirit you put to death the deeds of your sinful nature, you will live." (Romans 8)
These two powers operate by a set of laws: the law of sin and death and the law of the Spirit and life. The law of sin and death, which first began in the Garden, is established firm in us. The only way to rectify the law of sin and death is for another law to be established — a much better law. The better law is the law of faith, the law of the Spirit and life.
In Ester, we see that a law was given by the king to kill all Jews on a certain day. The king's law could not be revoked. So Mordecai with the king's signet established another law. This law brought life to the Jews because they could now defend themselves from the enemy's attack. These two laws fought against one another, but the second law, to fend for their lives, was more powerful than the first. The first law was established on hatred; the latter was established on love.
It is written: "Over 75,000 people are killed by the Jews, who are careful to take no plunder." (Ester 9) And the Bible makes no mention of any Jews being killed by their enemies! So here is my point: our Lord Jesus has rectified us and established us in His Spirit; and we are more than conquerors in Christ. The misdeeds of the flesh and its power and laws do not have any power over us who are led by the Spirit.
"You are of God, my little children, and have overcome them: because greater is he that is in you than he that is in the world." (1 John 4).
God's grace be with you.