It is important to understand the difference between sin and sins.  We *have* sin, and we *are* sinful.  We also commit sins.

Our state of being sinful results in us being under a just condemnation in the sight of God.  God, however, removes this condemnation and the penalty of our sign through our faith in Jesus.

> Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God.  John 3:18 ESV
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> Christ redeemed us from the curse of the law by becoming a curse for us—for it is written, “Cursed is everyone who is hanged on a tree”. Galatians 3:13 ESV

So, Christ's work on the cross and our faith in His finished work takes care of the penalty of sin.  However, we still commit sins.  This does not impact our destiny, but it does impact the intimacy of our relationship with God.  Through faith, we are born into the family of God, and we will forever be sons and daughters of God.  The relationship remains, but the intimacy suffers when we sin.  

This is true in our relationships with each other as well.  I will always be my father's son, but sometimes we have to ask forgiveness from each other to restore intimacy.