In Isaiah 9:6, the Everlasting Father of the A.V. really means the Father of Eternity or of the Everlasting. He is the Author of Eternity. The Greek philosopher Plato said that "time and the heavens came into being in the same instant in order that they might be dissolved together? of such was the mind of God in creation." Whatever might have been the thought in the mind of Plato expressed by that grandiloquent statement, we can rest assured that both fell far short of reality. Because the synchronising of the passage of time and the heavens is proximate and not final. They give place to the emergence of the new heavens and new earth which subsist in eternity!
In 2 Cor. 1:3, the expression "Father of Mercies, the God of all comfort" conveys that in these we find the most noteworthy in the realm of time. We are the objects not only of abstract mercy, but of ceaseless specific mercies, i.e., the countless incidents in which we are debtors to the mercy of God! In consequence He is the God of all comfort. The evidence of God's care for us must necessarily afford as nothing else can. He is the Author of those mercies, i.e., their origin.
In Heb. 12:9, consequent on discipline for our bodies, the expression "shall we not much rather be in subjection unto the Father of spirits and live" occurs. God is the Author of spirits, i.e., on the spiritual side man enters into intimate relation with God. Discipline is for the body, but it has the object in view of spiritual prosperity to the individual and as a consequence he lives; i.e., the effect of subjection to God's salutary discipline!
In James 1:17, we read that "every good gift and perfect gift is from above and comes down from the Father of Lights with Whom is no variableness neither shadow of turning." The service of God is enhanced by many brilliant lights, spreading the incomparable light of the Gospel and of the knowledge of the glory of God, far and wide. But these are not the result of natural evolution. They are not the legacy of inherent ability, but they have come as every good and perfect gift has come from above! God is the Author of these luminaries. So that the individuals who form the lamp-holders cannot take any credit to themselves, but it is very comforting to know that they emanate from an origin which knows no swerving in the consummation of His purpose. "The gifts and calling of God are without repentance (or retraction)" (Rom. 11:29).
In Eph. 1:17, the apostle puts as a preface to his first prayer therein "the God of our Lord Jesus Christ, the Father of Glory." That again shifts the centre of interest to eternity from which glory emanates and where its Author dwells. It is an unique usage. It has been suggested that the glory is synonymous with the glory of the Logos of John 1, which the disciples beheld; also with the glory of God in the face of Jesus Christ of 2 Cor. 4:6.