You have taken a circuitous route to post the same concept Paul plainly wrote in Galatians:
Galatians 3:23-29
23 But before faith came, we were kept in custody under the law, being shut up to the faith which was later to be revealed. 24 Therefore the Law has become our tutor to lead us to Christ, that we may be justified by faith. 25 But now that faith has come, we are no longer under a tutor. 26 For you are all sons of God through faith in Christ Jesus. 27 For all of you who were baptized into Christ have clothed yourselves with Christ. 28 There is neither Jew nor Greek, there is neither slave nor free man, there is neither male nor female; for you are all one in Christ Jesus. 29 And if you belong to Christ, then you are Abraham's offspring, heirs according to promise. NAS
Also you might try reading 1 John 3 in a modern translation since the KJ's antiquated translation is misleading.
1 John 3:4 Everyone who practices sin also practices lawlessness; and sin is lawlessness. NAS
As to Romans 7:7, have you read all of Romans?
Romans 8:1-11
8:1 There is therefore now no condemnation for those who are in Christ Jesus. 2 For the law of the Spirit of life in Christ Jesus has set you free from the law of sin and of death. 3 For what the Law could not do, weak as it was through the flesh, God did: sending His own Son in the likeness of sinful flesh and as an offering for sin, He condemned sin in the flesh, 4 in order that the 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 are according to the flesh set their minds on the things of the flesh, but those who are according to the Spirit, the things of the Spirit. 6 For the mind set on the flesh is death, but the mind set on the Spirit is life and peace, 7 because the mind set on the flesh is hostile toward God; for it does not subject itself to the law of God, for it is not even able to do so; 8 and those who are in the flesh cannot please God. 9 However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him. 10 And if Christ is in you, though the body is dead because of sin, yet the spirit is alive because of righteousness. 11 But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ Jesus from the dead will also give life to your mortal bodies through His Spirit who indwells you. NAS