One of the doctrinal pillars on which the "deity" of Jesus of Nazareth rests is the assiduous cultivation of the idea that Jesus was the “only-begotten son of God born of the Father before all ages”.
Expectations from the Hebrew Scriptures:
"I will declare the decree: YHWH hath said unto me, Thou art my Son; this day have I begotten thee."(Psalm 2:7)
"He shall cry unto me, Thou art my father, my God, and the rock of my salvation. Also I will make him my firstborn, higher than the kings of the earth." (Psalm 89:26-27)
The New Testament fulfillment:
"God hath fulfilled the same unto us their children, in that he hath raised up Jesus again; as it is also written in the second psalm, Thou art my Son, this day have I begotten thee. (Acts 13:33-34. Read from verse 16 to verse 42)
Shortly before making this utterance, Paul said of Jesus' birth -
"Of this man's (David's) seed, hath God according to promise, brought into Israel, a Saviour Jesus." (Acts. 13:23)
And again from Paul:
"Paul, a servant of Jesus Christ, called to be an apostle, separated unto the gospel of God,
(Which he had promised afore by his prophets in the holy scriptures,) Concerning his son Jesus Christ our Lord, which was made of the seed of David according to the flesh; And declared to be the son of God with power, according to the spirit of holiness, by the resurrection from the dead." (Romans 1:1-4)
"And he is the head of the body; the church: who is the beginning, the first-born from the dead." (Colossians 1:18, Revelation 1:5)
Jesus became the only-begotten son, the first-born from the dead, the first-fruits in the New Creation on the day of his resurrection.
Note that the following are also 'sons' of God and 'begotten of God':
"But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name: Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God." (John 1:12)