God is the father of all created things in that He is the source of all things that exist. But from Adam’s creation until Christ rose from the dead, He did not reveal Himself as Father. Until that time, only the Son, our Lord Jesus Christ, could speak of Him in the personal relationship of Father. But from eternity past it was His purpose to have a family of children brought into relationship with Himself as sons.
On the morning of His resurrection, our Lord Jesus expressed the joy of His heart and the Father’s heart when He said to Mary, “Go to My brethren, and say unto them, I ascend unto My Father, and your Father; and to My God, and your God” (John 20:1717Jesus saith unto her, Touch me not; for I am not yet ascended to my Father: but go to my brethren, and say unto them, I ascend unto my Father, and your Father; and to my God, and your God. (John 20:17)).
Now we enjoy this relationship of knowing God as our Father. The Spirit in us witnesses to our spirit, for we “have received the spirit of adoption, whereby we cry, Abba, Father” (Rom. 8:1515For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father. (Romans 8:15)).
As another has said, God is so pleased with His Son that He would have a whole family in heaven around Himself that are just like Him.
The Son of God became the Son of Man that we, the sons of men, might become the sons of God.