There are several issues to discuss about this.
Self-control is a fruit of the Spirit
(Gal 5:22) – as the Holy Spirit directs our lives and transforms us, it is His intention to build in us self-control. Becoming like Jesus is described as “sanctification” in the Bible – a progressive change where God builds holiness and His character in our lives.
Every Christian struggles with sin,
and the sin that has our attention will likely change over time. It is important to let God point out sin in our lives, and allow Him to change it in His timing and His way. If we try to pick a sin and exert self-effort to overcome it, we will likely fail. It is God who changes us, and rather than our self-attempts, focusing on our will power or our determination…God would rather we focus on Him and His power. He wants us to trust Him to change us, rather than trusting in ourselves.
Paul struggled with covetousness,
and describes this in Romans 7. The more he tried to obey the law, the more the law condemned him, because he couldn’t do it. His conclusion? When he asks, “who will free me from this body of sin and death?” his answer is, “Jesus” and proceeds to explain in Romans 8.
Other verses that may be helpful:
1 John 1:7-2:2 – Some excerpts from that: “If we say that we have no sin, we are deceiving ourselves and the truth is not in us. If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness…. My little children, I am writing these things to you so that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous; and He Himself is the propitiation for our sins…”
No one who is a Christian lives a perfect life, totally pleasing to God. But we are accepted by God due to Jesus’ death on our behalf, and we stand forgiven and declared righteous in God’s eyes because of Jesus’ righteousness.
Romans 3:20-26 – “Therefore no one will be declared righteous in His sight by observing the law; rather, through the law we become conscious of sin. But now a righteousness from God, apart from law, has been made known, to which the Law and the Prophets testify. This righteousness from God comes through faith in Jesus Christ to all who believe. There is no difference, for all have sinned and fall short of the glory of God, and are justified freely by His grace through the redemption that came by Christ Jesus. God presented Him as a sacrifice of atonement, through faith in His blood. He did this to demonstrate His justice, because in His forbearance He had left the sins committed beforehand unpunished– He did it to demonstrate His justice at the present time, so as to be just and the one who justifies those who have faith in Jesus.”
God says that we are no longer under the law (the demands and expectations of God) based on performance. Instead, we are under His grace, because Jesus fulfilled the demands of the law, and by His grace welcomed us into a relationship with Him.
The basis for eternal life is our faith in Jesus, not our ability to overcome sin. Jesus died on the cross because of our sin. He offers us forgiveness based on what He has done. He offers us righteousness before Him, acceptance as a child of God because He bought our salvation.
Our focus now is to be in His Word, asking Him to build into our lives what we see in the Bible, relying on Him to do it in us. Don’t get discouraged but continue to trust Him, continue to rest in His ability to change and free you from sin. Obey Him as He gives you a way of escape from temptation — take the way of escape! (1 Corinthians 10:13), but know that the transforming power belongs to Him, not to us.