"Some textbooks on Christian doctrine - Berkhof's, for instance - treat adoption as a mere sub-section of justification, but this is inadequate.The two ideas are distinct, and adoption is the more exalted. Justification is a forensic idea, conceived in terms of law and viewing God as judge. In justification, God declares of penitent believers that they are not, and never will be, liable to the death that their sins deserve, because Jesus Christ, their substitute and sacrifice, tasted death in their place on the cross. This free gift of acquittal and peace, won for us at the cost of calvary, is wonderful enough, in all conscience - but justification does not of itself imply any intimate or deep relationship with God the judge. In idea, at any rate, you could have the reality of justification without any close fellowship with God resulting. But contrast this, now, with adoption.Adoption is a family idea, conceived in terms of love, and viewing God as father. In adoption, God takes us into His family and fellowship, and establishes us as His children and heirs. Closeness, affection and generosity are at the heart of the relationship. To be right with God the judge is a great thing, but to be loved and cared for by God the father is greater."J.I. Packer