Do you understand Repentance?
Yes. Do you?
Repentance is an agreement with God that sin is wrong and a willingness to turn from it. The person who is willing to accept Jesus as savior is already reached the point that they agree with God that they are a sinner and have need of a Savior.
However, Repentance is not being perfect. Paul, as a Christian, struggled to live the Christian life. He said, "I do that which I don't want to do. And I don't do that which I know I ought to do.".
The Christian finds help throught the Holy Spirit to overcome sin. The Holy Spirit works with that initial humility that brought the Christian to the point of salvation to eventually transform the Christian into the image of Christ. However, this is not a quick process. And frankly, I doubt anybody actually completes it in this life.
Thus the scriptures exhort us to:
2 Peter 1:5 And beside this, giving all diligence, add to your faith virtue; and to virtue knowledge; 6 And to knowledge temperance; and to temperance patience; and to patience godliness; 7 And to godliness brotherly kindness; and to brotherly kindness charity. 8 For if these things be in you, and abound, they make you that ye shall neither be barren nor unfruitful in the knowledge of our Lord Jesus Christ.
Romans 12:2 - And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
Most new Christians don't have a clue just how sinful and different from the character of Christ they are. And it's often a long learning process that God takes us through to show us where sin continues to remain in us and to transform us into them image of Jesus. We won't be fully transformed until death or the rapture though, at which point we will see Jesus as he is, and we will put on the incorruptible.
1 Corinthians 15:52 - In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
1 John 3:2 - Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is.
My grandfather was an alcoholic when he was saved. He didn't immediately stop being an alcoholic. It took him about 9 months, before he realized that if he continue hanging with the same crowd, he was going to continue to get drunk, and changed his ways. He wasn't saved when he stopped being an alcoholic. He was saved 9 months before that. It just took 9 months for the Holy Spirit to work the changes in his thinking and behavior that needed to occur to help him to overcome this particular sin.