Some proclaim Paul said he could not help himself but kept on living in sin after receiving Christ. This misunderstanding comes from Chapter 7 in Romans. Where Paul is speaking of a life outside of Christ's Spirit. Please give it a read. But remember The context continues in chapter 8 where Paul through the Spirit speaks of being delivered from the Law of Sin and death in which he was in captivity, Condemning sin in the flesh that the righteousness of the law be fulfilled in us. Please look at the text below as he continues after giving his testimony prior to Christ.
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 shall deliver me from the body of this 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. There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit. For the law of the Spirit of life in Christ Jesus HATH MADE ME FREE FROM THE LAW OF SIN AND DEATH. For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin,CONDEMNED SIN in the flesh: That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit.
(Rom 7:23-8:4 KJV)