What makes Jesus god's son?
God didn't impregnate anyone to get little Jesus started.
God didn't stay by Mary as she went through the trials of pregnancy in a primative age.
God wasn't there at the birth coaching and helping Mary through the delivery.
God didn't raise little Jesus and teach him how to play ball.
What sacrifices did god make in order to bring Jesus up? Where and when did the bonding take place?
There is no reference to God having anything to do with Jesus until we learn about them being father and son (yet at the same time "one") thirty to forty years AFTER the death of Jesus.
So what, other than decree, makes Jesus, god's "only begotten son"?
God was an absentee father.