Ephesians 6:10-20 talks about the Armor of God give by God to the believer. God never saves the person and just leaves them alone. Hebrews 13:5 says that God will never leave nor forsake the believer. With that promise in hand, there is the confidence that the believer overcomes sin because they have that power only from their Heavenly Father. Philippians 1:6-7 raises the confidence that what God has begun in the believer it is bound to be finished on the day of the Lord Jesus Christ. 1 John 4:18 says perfect love casts out any fear for the world. The fear of the LORD is not terror to the believer but reverential fear.
Jeremiah 17:5 says that cursed are the people who trust in man and makes flesh his arm. The reality is you cannot trust your flesh. Romans 7:17-25 makes it clear that the Apostle Paul struggled with sin even if he no longer lives like the rest of the unsaved world. When it comes to fighting sin, it is always ask God for the strength to overcome it and not rely on one's self. With constant fellowship with God in both prayer and fellowship then good works and witnessing becomes effective. The power of God is the only thing that makes the Christian stand firm from the noise raised by the world.