Rom. 8:12-14 So, dear brothers and sisters, you have no obligation whatsoever to do what your sinful nature urges you to do. For if you keep on following it, you will perish. But if through the power of the Holy Spirit you turn from it and its evil deeds, you will live. For all who are led by the Spirit of God are children of God.
One of the things that sets apart true believers from the rest is how they are affected by sin. A child of God is not under obligation to sin when tempted. Without Christ, the natural thing to do is not resist the temptation and plunge right into sin. We are to stand up against Satan and not give in to sinful urges. With Christ's help, we are able to do that.
The reality of it is, if we keep falling into sin, we will fall so deep into it that we will not be able to find our way out of it and into fellowship with God. The end result of all sin is eternal separation from God. Hell awaits those who live in sin and stay there. The only hope we have is to let the Holy Spirit take us by the hand and lead us out of sin to Calvary.
When we turn to Christ for the forgiveness of sin, we turn away from sinful living. We do not continue to live like we have lived. We stand up to Satan and say no to sin. We seek instead to live holy lives before God. God's children do not seek to sin against God. We are not perfect and will sin, but it is not what we normally do. Instead, we seek to do what we know is right before God and please Him. Pleasing Him becomes the desire of our hearts instead of pleasing ourselves or others.
If you are not being led by the Holy Spirit away from a life of sin, you are not a child of God.