Herein lies the problem. You are reading Romans 7:14-23 out of context. That describes those under the law - without the Spirit. They aren't saved, but under the Old Covenant. Their problem was SIN, because of not being born again of the Spirit. They could only obey the letter of the law, but their sin nature caused them to be double minded. The previous verses shows you the context, and then chapter 8 shows how to be free of the law by obey the Spirit.
Romans 7:
4 Therefore, my brethren, you also have become dead to the law through the body of Christ, that you may be married to another—to Him who was raised from the dead, that we should bear fruit to God. 5 For when we were in the flesh, the sinful passions which were aroused by the law were at work in our members to bear fruit to death. 6 But now we have been delivered from the law, having died to what we were held by, so that we should serve in the newness of the Spirit and not in the oldness of the letter.
Sin’s Advantage in the Law
7 What shall we say then? Is the law sin? Certainly not! On the contrary, I would not have known sin except through the law. For I would not have known covetousness unless the law had said, “You shall not covet.” 8 But sin, taking opportunity by the commandment, produced in me all manner of evil desire. For apart from the law sin was dead. 9 I was alive once without the law, but when the commandment came, sin revived and I died. 10 And the commandment, which was to bring life, I found to bring death. 11 For sin, taking occasion by the commandment, deceived me, and by it killed me. 12 Therefore the law is holy, and the commandment holy and just and good.
Law Cannot Save from Sin
13 Has then what is good become death to me? Certainly not! But sin, that it might appear sin, was producing death in me through what is good, so that sin through the commandment might become exceedingly sinful.
Romans 8 - Spirit
There is therefore now no condemnation to those who are in Christ Jesus, who do not walk according to the flesh, but according to the Spirit. 2 For the law of the Spirit of life in Christ Jesus has made me free from the law of sin and death. 3 For what the law could not do in that it was weak through the flesh, God did by sending His own Son in the likeness of sinful flesh, on account of sin: He condemned sin in the flesh, 4 that the righteous requirement of the law might be fulfilled in us who do not walk according to the flesh but according to the Spirit. 5 For those who live according to the flesh set their minds on the things of the flesh, but those who live according to the Spirit, the things of the Spirit. 6 For to be carnally minded is death, but to be spiritually minded is life and peace. 7 Because the carnal mind is enmity against God; for it is not subject to the law of God, nor indeed can be. 8 So then, those who are in the flesh cannot please God.
9 But you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. Now if anyone does not have the Spirit of Christ, he is not His.