God, technically, has only one "only begotten Son": Jesus (Jn. 1:14, 18; 3:16, 18; Heb. 11:17; 1 Jn. 4:9)! By "technically," I mean God, in the Person of the Holy Spirit, literally caused Mary to be "with child," in what is known as the Incarnation, that is, God being born physically as a Man (Matt. 1:18; Jn. 1:1, 14) By "begotten," I mean the same thing as Matthew meant with all his "begats." (Matt. 1:2-16). Born again believers are also said to be "begotten of God," but this phrase refers to being born again spiritually (Jn. 3:3-8; Jam. 1:18; 1 Jn. 5:1).
Born again believers are also related to God in the physical sense, in that, we are all adopted by Him. The Apostle Paul wrote, "For as many as are led by the Spirit of God, they are the sons of God. For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father. The Spirit itself beareth witness with our spirit, that we are the children of God" (Rom. 8:14-16). Paul continued, "And not only they, but ourselves also, which have the firstfruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, to wit, the redemption of our body" (Rom. 8:23). Paul also described the children of Israel as being adopted by God. He wrote: "Who are Israelites; to whom pertaineth the adoption, and the glory, and the covenants, and the giving of the law, and the service of God, and the promises" (Rom. 9:4).
Paul repeated his teaching on God being our adopted Father in his letter to the Church at Galatia. He wrote, "Even so we, when we were children, were in bondage under the elements of the world: but when the fulness of the time was come, God sent forth his Son, made of a woman, made under the law, to redeem them that were under the law, that we might receive the adoption of sons. And because ye are sons, God hath sent forth the Spirit of his Son into your hearts, crying, Abba, Father" Gal. 4:3-6).
I believe that we being "spiritually fatherless," live in an "orphanage" known as the world. What is worse, we don't even realize we are "orphans." At a time of His choosing, God sends His Spirit to convince us of our status as being dead in sin, and in need of being born again (Jn. 3:6-8; 16:7-15; Eph. 2:5). The Holy Spirit "offers" us the gift of adoption (salvation - Eph. 2:8), and we must choose to allow God to adopt us (Jn. 1:12; Rom. 10:8-17; etc.).
God offers to be our Father, but we must choose to accept His offer. Have you?