Son of God
The title "Son of God" is asserted of the Lord Jesus Christ in three different applications.
First: He is "Son of God" in incarnation.
“Thou art My Son; this day have I begotten Thee." Psa. 2:7. Here it is in connection with His kingship in Zion, presented to Israel at His first coming, but postponed till His second, because of their unbelief then and now. So Jehovah's King was Jehovah's Son before He was begotten in time. So also in Isa. 9:6: "Unto us a child is born, unto us a son is given.”
Compare Luke 1:32: "He shall be great, and shall be called the Son of the Highest; and the Lord God shall give unto. Him the throne of His father David." And further in verse 35: "Therefore also that holy thing which shall be born of thee shall be called the Son of God.”
Second: He is "Son of God" as risen from the dead.
Acts 13:33, 34 shows Jesus in two positions: verse 33 as raised upon earth and verse 34 as raised up from the dead. See also Col. 1. where verse 15 seems to refer to His birth into the world, and where He necessarily was the firstborn or chief of every creature as being the Creator. In verse 18 the reference is to His place of preeminence as risen, "who is the beginning, the firstborn from the dead." Heb. 1:5 speaks of Him in the first of these two positions; verse 6 probably in the second, especially if the marginal reading (which is most likely the correct one) be taken. This would connect His introduction into the habitable world with His second coming. Rev. 1:5 may confirm this.
Third: Heb. 1:1-3 evidently speaks of our Lord as Son in the highest sense, that is, as divine.
So it is almost everywhere in the gospel and epistles of John. "The only begotten of the Father" does not refer to His place as born on earth or risen from the dead, but expresses His eternal relationship as a divine Person.
Son of Man
John 5 shows us the Son quickening whom He will in virtue of His divine glory, and it declares that all judgment is committed to Him as Son of man. This title refers to His assumption of that nature in which He is first rejected, and secondly, exalted as universal Lord and Judge. (See Psa. 8 compared with Heb. 2, Dan. 7, and the Gospels.) Also He is seen as "the Son of man" in connection with the judgment of the seven churches in Rev. 1. That is why cherubim as the witness of judgment were wrought on the veil, the type of His flesh.
Bible Witness and Review