I think both Judaism and Christianity are not now the Original Religion taught by their prophets. But at the same time, there are many beliefs and traits of the Original Religion of God still existing in those two religions; however, even if the title "son of God" was used by Jesus himself one should remember the following points:1. As a biblical scholar said, "Semitic usage would never have allowed literal sense even though such an expression would be interpreted literally in the Hellenistic world of Jesus followers".
2.The New Testament Greek words used for "son" are pias and paida, which means 'servant' or 'son in the sense of servant, are translated son in reference to Jesus and servant in reference to others in some translations of the Bible (Mufassir, P. 15).
3. The title "son of man" which is a self-designation of Jesus and occurs 81 times in the gospels is the clearest description and emphasis by Jesus on his humanity. The classical interpretation given to this title is that it is used to emphasize the human side of Jesus. Now the question which suggests itself is: Do contemporary Christians emphasize this aspect of Jesus?
Now, as a total contrast we turn to Christianity a religion built not around God, or His book for there was no 'book’ until 150 years after Jesus' death. Christianity became built around the personality of Jesus himself. By laying more and more stress upon the magnetic and wonderful personality of Jesus and unable and un-willing to describe the Prophet's effect upon all who came to him in everyday terms more and more attributes are added to his reputation a man who could perform miracles, bring back the dead to life, heal the leper, cure the blind all by God’s will, is indeed a wonderful man blessed by God born by God’s will to do His service. But after his death, the 'magical' personality must be kept alive and 'Son of God' appears to suitably qualify all his actions.
Living in a society, strongly flavored by the Greco-Roman gods, all 'super human,' the educated early Christians must surely also have been influenced in thought by their surroundings. Paul himself, one of the great teachers of Christianity, was a Hellenized Jew, who never saw or met Jesus during his lifetime. Yet many of his reported sayings show the influence of the times in which he lived. 'The Living Lord' was very real to him.
The miraculous nature of Jesus' birth also could help to give credence to the idea of Jesus identity as son of God. But it is child-like in its 1 + 1 = 2 type philosophy, i.e., God blew into the womb of Mary had Jesus, therefore God is Jesus' father and Jesus is His son.
What Christians fail to see, and to understand is that in Jesus' birth and conception we see a touching and wonderful revelation of the Kindness of God.
I will repeat what I mentioned before, both the Bible and the Quran, because, both the Bible and the Quran teach that Jesus is not God.