I was recently in a discussion about the salvation of an individual and how one can be assured that they won't "lose" their salvation. Here is my response:
Our salvation is provided by Christ and Christ alone. It is not of righteousness lest any should boast. It is not of our works in any way. If we had to work for our salvation, the work of Christ on the cross would not have been necessary. Man can not atone for his sin because the gulf of separation between God and sinful man is too great. It takes the perfect righteousness of Christ and His atoning work to provide our salvation.
Therefore, since our atonement is in the perfect righteousness of Christ, once we have recognized our need of redemption and have accepted Christ's all sufficient work on the cross, we become one of the forgiven, adoptive children of God.
As a child of God, we may not please Him in things we do. We may not walk close by His side. We may actually anger God by our disobedience. We are, however, His children. We are His.
The story of the prodigal is often used to portray a sinner who comes to God (the Heavenly Father). I see it, too, as the portrayal of a son who has strayed and returned to the Father. We as children of God (redeemed children of God) may stray, we may displease our Father, but we can return to His open and loving arms.
In a nutshell, we are always the beloved child of the Father once we are adopted (born again) into His family.