You appear to think that the Bible does not teach you can overcome grievous sin because even Paul struggled with sin as a Christian. But if you don't believe my Scriptural points on Romans 7, I have provided below a list of verses that plainly state that you can overcome grievous sin in this life.
"There hath no temptation taken you but such as is common to man: but God is faithful, who will not suffer you to be tempted above that ye are able; but will with the temptation also make a way to escape, that ye may be able to bear it." (
1 Corinthians 10:13).
"But put ye on the Lord Jesus Christ, and make not provision for the flesh, to fulfil the lusts thereof." (
Romans 13:14).
"And they that are Christ's have crucified the flesh with the affections and lusts." (
Galatians 5:24).
1 "Forasmuch then as Christ hath suffered for us in the flesh, arm yourselves likewise with the same mind: for he that hath suffered in the flesh hath ceased from sin;
2 That he no longer should live the rest of his time in the flesh to the lusts of men, but to the will of God." (
1 Peter 4:1-2).
"Having therefore these promises, dearly beloved, let us cleanse ourselves from all filthiness of the flesh and spirit, perfecting holiness in the fear of God." (
2 Corinthians 7:1).
"This I say then, Walk in the Spirit, and ye shall not fulfil the lust of the flesh." (
Galatians 5:16).
"Be careful to live properly among your unbelieving neighbors. Then even if they accuse you of doing wrong, they will see your honorable behavior, and they will give honor to God when he judges the world." (
1 Peter 2:12 NLT).
"That ye may be blameless and harmless, the sons of God, without rebuke, in the midst of a crooked and perverse nation, among whom ye shine as lights in the world;" (
Philippians 2:15).
“Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin. For he that is dead is freed from sin. Now if we be dead with Christ, we believe that we shall also live with him” (
Romans 6:6-8).
“Don't you realize that you become the slave of whatever you choose to obey? You can be a slave to sin, which leads to death, or you can choose to obey God, which leads to righteous living.” (
Romans 6:16 NLT).
“there are false prophets... who cannot cease from sin.” (
2 Peter 2:1,
2 Peter 2:14).
(Note: While this verse is not specifically talking about overcoming sin, it is implying that by the fact that false prophets are defined here in the fact that they cannot cease from sin).
“Awake to righteousness, and sin not; for some have not the knowledge of God: I speak this to your shame.” (
1 Corinthians 15:34).
“Now the God of peace, that brought again from the dead our Lord Jesus, that great shepherd of the sheep, through the blood of the everlasting covenant, Make you perfect in every good work to do his will, working in you that which is well pleasing in his sight, through Jesus Christ; to whom be glory for ever and ever. Amen” (
Hebrews 13:20-21).
“But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him.” (
1 John 2:5).
“And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ.” (
1 Thessalonians 5:23).
“For this is the will of God, even your sanctification, that ye should abstain from fornication: That every one of you should know how to possess his vessel in sanctification and honour;” (
1 Thessalonians 4:3-4).
“For God hath not called us unto uncleanness, but unto holiness.” (
1 Thessalonians 4:7).
“And we know that we are of God, and the whole world lieth in wickedness.” (1 John 5:19).
Memorize these verses and put them on the inside of your heart.