To me, Psalm 2 is one of the most important parts of the Bible in terms of the relationship between God the Father and God the Son.
Psalm 2; Let’s read through it with prayerful heart, so God the Holy Spirit enables us to understand clearly about this truth.
1Why do the nations conspire
and the peoples plot in vain?
2The kings of the earth take their stand
and the rulers gather together
against the Lord
and against his Anointed One.
3“Let us break their chains,” they say,
“and throw off their fetters.”
4The One enthroned in heaven laughs;
the Lord scoffs at them.
5Then he rebukes them in his anger
and terrifies them in his wrath, saying,
6“I have installed my King
on Zion, my holy hill.”
7I will proclaim the decree of the Lord:
He said to me, “You are my Son
today I have become your Father.
8Ask of me,
and I will make the nations your inheritance,
the ends of the earth your possession.
9You will rule them with an iron scepter;
you will dash them to pieces like pottery.”
10Therefore, you kings, be wise;
be warned, you rulers of the earth.
11Serve the Lord with fear
and rejoice with trembling.
12Kiss the Son, lest he be angry
and you be destroyed in your way,
for his wrath can flare up in a moment.
Blessed are all who take refuge in him.
Pay a special attention to Psalm 2:7;
I (=the Messiah, pre-incarnate Jesus) will proclaim the decree of the LORD: He said to me, "You are my Son; today I have become your Father.
The word ילדתי yalidti, "I have begotten," is here taken in the sense of manifesting, exhibiting, or declaring; and to this sense of it St. Paul (Romans 1:3, Romans 1:4) evidently alludes when speaking of "Jesus Christ, who was made of the seed of David according to the flesh, του ὁρισθεντος Υἱου Θεου εν δυναμει, κατα Πνευμα αγιωσυνης, εξ αναστασεως νεκρων; and declared (exhibited or determined) to be the Son of God with power, according to the Spirit of holiness, by his resurrection from the dead"
This can be well interpreted; “This very rejected Person, I(God the Father)), this day, by raising Him(the Son) from the dead, and placing Him at my right hand, giving to Him all power in heaven and earth, declare to be my Son, the Beloved One in Whom I am well pleased. Therefore hear Him, believe on Him, and obey Him; for there is no redemption but through His blood; no salvation but in His name; no resurrection unto eternal life but through his resurrection, ascension, and powerful intercession at My Right Hand. He is My Son.”
The name "sons of God," is applied in the Scriptures to saints, and may have been given to the angels. But the argument here is that the name, "My Son" has never been given to any one of them particularly and by eminence. In a large general sense, they are the sons of God, or the children of God, but the name is given to the Lord Jesus, the Messiah, in a special sense, implying a unique relation to him, and a special dominion over all things.
Hebrews 1:5-12 reads;
5For to which of the angels did God ever say,
“You are my Son;
today I have become your Father?
“I will be his Father,
and he will be my Son”?
6And again, when God brings his firstborn into the world, he says,
“Let all God’s angels worship him.”
7In speaking of the angels he says,
“He makes his angels winds,
his servants flames of fire.”
8But about the Son he says,
“Your throne, O God, will last forever and ever,
and righteousness will be the scepter of your kingdom.
9You have loved righteousness and hated wickedness;
therefore God, your God, has set you above your companions
by anointing you with the oil of joy.”
10He also says,
“In the beginning, O Lord, you laid the foundations of the earth,
and the heavens are the work of your hands.
11They will perish, but you remain;
they will all wear out like a garment.
12You will roll them up like a robe;
like a garment they will be changed.
But you remain the same,
and your years will never end.”
13To which of the angels did God ever say,
“Sit at my right hand
until I make your enemies
a footstool for your feet”?
14Are not all angels ministering spirits sent to serve those who will inherit salvation?
When Jesus was baptized by John the Baptist, a voice was heard from Heaven, “As soon as Jesus was baptized, he went up out of the water. At that moment heaven was opened, and he saw the Spirit of God descending like a dove and lighting on him. 17And a voice from heaven said, “This is my Son, whom I love; with him I am well pleased.”(Matthew 3:16-17)
Apostle Paul quoted from Psalm 2 when he and Barnabas went to synagogue in Antioch, Pisidia and preached to them;
“And now we are here to bring you this Good News. The promise was made to our ancestors, and God has now fulfilled it for us, their descendants, by raising Jesus. This is what the second psalm says about Jesus: You are my Son. Today I have become your Father.”
The disciples heard a voice from Heaven on the Mount of Transfiguration, “While he was still speaking, a bright cloud enveloped them, and a voice from the cloud said, This is my Son, whom I love; with him I am well pleased. Listen to him!" (Matthew 17:5 )
Jesus’ calling Himself to be the Son of God became the ground for the Jews to kill Him, “For this reason the Jews tried all the harder to kill him; not only was he breaking the Sabbath, but he was even calling God his own Father, making himself equal with God.” (John 5:18)
Most important thing for you and me is, “The Son of God is our Lord Jesus whom I and you call “Everlasting Father”(Isaiah 9:6 reads; For to us a child is born, to us a son is given, and the government will be on his shoulders. And he will be called Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace.). Just as God the Father begat His Son Jesus, our Lord Jesus bore you and me with His blood and water shed for us on the cross! Amen and amen.