A person who makes a genuine commitment of his or her life to Christ becomes a child of God and a member of God's family (John 1:12).
Just as an orphaned child is adopted into a family, so are we adopted by God and made a part of His family forever. And some day we will go to be with Him in heaven. "How great is the love the Father has lavished on us, that we should be called children of God! And that is what we are!" (1 John 3:1).
However, just because we have committed our lives to Christ does not mean we will no longer struggle with temptation, and sometimes sin. Even the great apostle Paul could say, "I find this law at work: When I want to do good, evil is right there with me" (Romans 7:21).
When we do sin, God does not reject us or disown us. Our fellowship with Him may be broken, but our relationship is not; we are still members of His family if we have truly committed our lives to Christ. When we sin we should immediately turn to God, confess our sin honestly, ask His forgiveness and then turn from our sin.
The Bible promises, "If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness" (1 John 1:9).
If we truly know Christ and are seeking to follow Him, we will not be complacent and unconcerned about sin in our lives. In fact, one of the signs of true spiritual life is the hatred of sin and the determination to conquer it. We will not continue to repeat the same sins over and over again, but will seek God's help (by the Holy Spirit who dwells within us) to overcome them.
The Bible promises, "No temptation has seized you except what is common to man. And God is faithful; he will not let you be tempted beyond what you can bear. But when you are tempted, he will also provide a way out so that you can stand up under it" (1 Corinthians 10:13). Indifference to sin in one's life is a sure sign of serious spiritual sickness, and may indicate that one has never truly invited Jesus into one's life as Savior and Lord (1 John 2:3-4).