What is the day of the ‘begottenness’ of Jesus as the Son?” It’s the day of resurrection. The day Jesus was begotten as the Son of God was not the day He was created; it was the day He resurrected and the day God the Father enthroned Him, or installed Him, as the Messianic ruler with all the full authority and rights and privileges that come with that office. He was begotten, that is, enthroned and installed, as the Son, a messianic term, on the day of His resurrection. The term has nothing to do with the Son of God being a begotten or created being. Many critics try to bring in a ‘created position’ but it does not fit based on the context of Psalm 2.
A little bit of research into Psalm 2 underscores the messianic context of Psalm 2:7. This is a descriptive praise psalm that is also a royal psalm. Royal psalms were written for the reigning king of the house of David. They praise God in a general manner for His goodness through the exploits of the Davidic king. In some of these psalms, however, the exploits go well beyond what any Davidic king accomplished. Such fulfilment could only be found in the ultimate Son of David, the Messiah. In Him all of the expectations of the sons of David reach their culmination. In this sense Psalm 2 is an indirectly messianic psalm (like
Psalms 45 and 72) where the psalmist’s language far exceeds application to the present Davidic king.
This is why the New Testament writers demonstrate that the messianic expectations of Psalm 2:7 were fulfilled in Jesus of Nazareth. At Jesus’ resurrection from the dead, He was finally and definitively appointed and installed into the messianic office. He was “begotten” as the Messiah. He was “declared the Son of God with power by the resurrection from the dead” (Rom. 1:4, emphasis added). Psalm 2:8, further, declares that Messiah is given a coronation gift: “Ask of Me, and I will surely give the nations as Thine inheritance, And the very ends of the earth as Thy possession.” This can clearly been seen on earth as Christianity has got the widest following.
Psalm 2[the whole Psalm] is an inauguration psalm for the Israelite kings—the public declaration of kingship. And most of the Kings became kings as grown men. None became king at his conception. And this meaning carries over into the New Testament use for Jesus just as well, that the resurrection is the public announcement by God about the true identity and authority of Jesus, Messiah, true king of Israel, representative of God among mankind.
The context in Psalm 2 is the key to understanding the message. It is absolutely clear that this was no physical birth. This psalm speaks of a grown person who is inaugurated as the king of God’s people, and the term “yawlad” denotes the giving of the authority and power of God’s Spirit. When Psalm 2:7 is quoted in the Injil as referring to Jesus Christ, the Greek word “gennao” which can have a physical or spiritual meaning is used for “yawlad.” Again the context is very clear. A spiritual anointing is proclaimed.
This is a prophetic Psalm and verse 7 refers to the resurrection of Christ, when He became “the first begotten from the dead” (Revelation 1:5) and “the firstborn from the dead” (Colossians 1:18) These terms must be understood in its original language.
Psalm 2:7-Verse 7 - Thou art my Son This day have I begotten thee. BY THE RESURRECTION thou art declared to be the Son of God, by miraculous power, being raised from the dead. Thus by thy wondrous and supernatural nativity, most extraordinary death, and miraculous resurrection, thou art declared to be the Son of God.