The reason that many continue in sin is because they have no power over sin. Many have tried to sincerely repent over and over and that didn't work. They cried out to God in their weakness and asked God to overcome their sin for them and it did not happen. They tried to restrain themselves and for awhile they had victory but went right back into it. After all that they gave up and said the heck with it. God must not want to give me victory over my sin and they backslid and didn't care what happened to them or what others thought about them. They probably thought they lost their salvation and that God didn't care about them any longer and gave up on them. EVERY SINGLE THOUGHT THEY HAD ABOUT NOT GETTING VICTORY OVER SIN AND WHAT GOD THINKS ABOUT THEM IS ABSOLUTE LIES! And those lies did not come from God or His word either.
The reason they don't have victory over sin is because they have the wrong idea about what God did on the cross to their sin, they don't understand positional truth from God's viewpoint and they are not receiving grace that would give strength in their weakness. Because of these things they live in guilt and condemnation when they sin and are never built up and edified by God's word and don't realize that the blood of Christ covers them when they sin just as much as when they don't sin. The are instantly defeated in their mental attitude when the thought of sin enters their mind and they are drawn away of their own lust and enticed with no power through grace to live in victory over sin.
I have plenty more I would like to say but I will leave it there for now. One last thing. Jesus Christ died for the sins of the world / 1Jn 2:2, that is for every single sin from every man born under heaven, that would ever be committed in this life, past, present, future and with no exceptions. If that was not true then His sacrifice and atonement would be incomplete and His blood would be limited in its power it has to cleanse us from ALL sin and justify the ungodly. You want the verses on this, I'll give them to you on the next post, and there are plenty.