John 1:49. Son of God; King of Israel
Nathanael answered and saith unto him, Rabbi, thou art the Son of God; thou art the King of Israel.
//Note the semicolon in today’s verse. What you’re reading is a form of Hebrew poetry (though written in Greek, of course), known as parallelism. Nathanael seems to make two claims: (1) Jesus is the Son of God, and (2) Jesus is the King of Israel.
But this is not what Nathaniel meant. Readers of a Hebrew mindset would immediately recognize that the second half of the claim is a restatement of the first. In Nathanael’s mind, the two statements are one and the same, just poetically reinforced. Only the Son of God could be King of Israel; only the King of Israel could be the Son of God.
Throughout Israel’s history, its kings were known as divinely-appointed representatives of God. They were called sons of God. The difference with Jesus, of course, is that he is the son of God, not merely a son of God. He is understood by Nathaniel to be the final, greatly-anticipated king, whom God would raise up to rule forever. The Jewish Messiah.
We can use this understanding to shed light on other places where the phrase “Son of God” is used. Take this passage written by Paul to the Romans. It has nothing whatsoever to do with being the literal offspring of God.
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 1:3-4
Paul was an adoptionist before the term ever became known; he understood that Jesus became the Son of God at his resurrection. That is because Paul recognized Jesus as being anointed king at the moment he rose from the dead. Jesus was born of men, a descendant according to the flesh, and declared to be the Son of God after he died … and God raised him up to be his Son.