How do I stop repeating sins?

Answer:

Part of your difficulty is that you are expecting something from being a Christian that doesn't exist. Just because you became a Christian, it doesn't mean that your struggle against sin ceases. "This is the message which we have heard from Him and declare to you, that God is light and in Him is no darkness at all. If we say that we have fellowship with Him, and walk in darkness, we lie and do not practice the truth. But if we walk in the light as He is in the light, we have fellowship with one another, and the blood of Jesus Christ His Son cleanses us from all sin. If we say that we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. If we say that we have not sinned, we make Him a liar, and His word is not in us" (1 John 1:5-10). Though written to Christians to encourage us not to sin, John says that any Christian claiming to be without sin is lying.

To expect that temptation would cease is to expect that Satan would give up his struggle against God. "Be sober, be vigilant; because your adversary the devil walks about like a roaring lion, seeking whom he may devour" (I Peter 5:8). It is just not going to happen. The temptation is the result of Satan placing us in situations where it seems that to get something we want, we must first break a law of God. A Christian can't control whether he will be tempted. Temptations are going to happen because Satan wants us to fail. We can wage war as to whether we will seriously consider breaking God's law, but we can't stop the temptation that precedes it. God helps us overcome temptations, He puts limits on what Satan can do, but He doesn't stop them. "No temptation has overtaken you except such as is common to man; but God is faithful, who will not allow you to be tempted beyond what you are able, but with the temptation will also make the way of escape, that you may be able to bear it" (I Corinthians 10:13).

There is a whole section devoted to the struggles every Christian must face. "For we know that the law is spiritual, but I am carnal, sold under sin. For what I am doing, I do not understand. For what I will to do, that I do not practice; but what I hate, that I do. If, then, I do what I will not to do, I agree with the law that it is good. But now, it is no longer I who do it, but sin that dwells in me. For I know that in me (that is, in my flesh) nothing good dwells; for to will is present with me, but how to perform what is good I do not find. For the good that I will to do, I do not do; but the evil I will not to do, that I practice. Now if I do what I will not to do, it is no longer I who do it, but sin that dwells in me. I find then a law, that evil is present with me, the one who wills to do good. For I delight in the law of God according to the inward man. But I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members. O wretched man that I am! Who will deliver me from this body of death? I thank God--through Jesus Christ our Lord! So then, with the mind I myself serve the law of God, but with the flesh the law of sin" (Romans 7:14-25). Paul states that intellectually he knows what he ought to do and it is his desire to do as he ought. However, he constantly finds himself doing things that he knows is wrong. The very fact that the struggle exists is evidence that Paul agrees with God's law that certain actions are wrong, but still, the struggle continues.

What is a Christian to do? When he finds himself in sin, he confesses his errors to God (I John 1:9), trusts that God will forgive him, picks himself up and tries again. "My little children, these things I write to you, so that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous. And He Himself is the propitiation for our sins, and not for ours only but also for the whole world. Now by this we know that we know Him, if we keep His commandments" (I John 2:1-3). A child of God aims for a sinless life while accepting the fact that he is going to stumble along the way. He might sin, but he refuses to wallow in his sins and remain in them. That is the difference between the true Christian and the followers of Satan. People in the world sin and make no effort to correct them. Oh, they might do some things right once in a while, but they don't remain in righteousness. This is the point of I John 3:1-10.

Rather than focusing on your past mistakes, get your eyes back on the goal. "Not that I have already attained, or am already perfected; but I press on, that I may lay hold of that for which Christ Jesus has also laid hold of me. Brethren, I do not count myself to have apprehended; but one thing I do, forgetting those things which are behind and reaching forward to those things which are ahead, I press toward the goal for the prize of the upward call of God in Christ Jesus" (Philippians 3:12-14). You can't win the race sitting on the track pouting that you've fallen too many times. Neither sitting or pouting is going to get you across the finish line.