The second connection in which the New Testament speaks of God as Father has to do with the believing sinner’s adoption into the life of God’s family. This is a supernatural gift of grace, linked with justification and new birth, given freely by God and received humbly by faith in Jesus Christ as Savior and Lord. “To all who received him [Jesus], who believed in his name, he gave power to become children of God who were born . . . of God . . .” (John 1:12ff). The message Jesus sent to his disciples on rising from the dead was: “I am ascending to my Father and your Father, to my God and your God” (John 20:17). As disciples, they belonged to the family; indeed, in that very sentence Jesus called them “my brethren.” All whom he has saved are his brothers.
When the Christian says the first clause of the [Apostles'] Creed, he will put all this together and confess his Creator as both the Father of his Savior and his own Father through Christ—a Father who now loves him no less than he loves his only begotten Son. That is a marvellous confession to be able to make.
J.I. Packer, Growing in Christ, p. 29