One problem Trinitarians face is that Jesus was born, and came into existence, which makes us wonder how can he be God, since God is eternal and always existed. To solve this problem Trinitarians came up with the idea that Jesus always existed, even before he went and came out of the womb, he was already in existence, Christians argue that the figure known as the Angel of the Lord which is seen in the Old Testament is the pre-existent Jesus (Before he went and came out of the womb).
I have already dealt with the issue of Jesus supposedly being the Angel of the Lord, the articles can be read on the following links:
So with that said let us go to the Book of Hebrews, a book of the New Testament, let us go specifically to chapter one to see what the author said concerning Jesus:
In the past God spoke to our forefathers through the prophets at many times and in various ways, but in these last days he has spoken to us by his Son (Hebrews 1:1-2)
The above verse is a great refutation to the argument that Jesus was always in existence, as the verse says, God has spoken to people in the past through several means, including prophets, and now in the last days he has spoken to us through his Son, namely Jesus. Therefore this means that God has only begun to use Jesus during the last days, and Jesus wasn't being used before in the past, surely if Jesus existed eternally, and acted as an agent during the Old Testament times (as the Angel of the Lord), then the author of Hebrews would have mentioned it, yet the author of Hebrews makes it clear that Jesus was not an agent of God until the LAST DAYS, basically the present days of when Hebrews was written.
Christian Unitarian scholars also took note of this, as they write:
A text which surveys God's activity over the ages says, "God spoke long ago to the fathers through prophets in many portions and in many ways, but [in contrast] in these last days has spoken to us in His Son" (Heb. 1:1-20). This would seem to confirm that until his human birth Jesus was not Son of God nor God's messenger to man. This same book of Hebrews points out that the Word was spoken through angels in the Old Testament times (Heb. 2:2). If the message to Israel was through the same preexistent Jesus who became man, the writer of this New Testament book seems to lack any such information. Messages were given through prophets and angels certainly, but never was there a hint that the Old Testament message was transmitted through the one who later came to be identified as the Son. (Anthony F, Buzzard, Charles F, Hunting. The Doctrine of the Trinity, Christianity's Self-Inflicted Wound. International Scholars Publications, 1998. PP. 108)
Another New Testament book that shatters the supposed preexistence of Jesus comes from Colossians, which says:
He is the image of the invisible God, the firstborn over all creation(Colossians )
According to Paul Jesus is the firstborn of CREATION! This means that Jesus is therefore part of creation, and isn't preexistent.
So in conclusion this makes it all clear that Jesus is indeed a created being, and that he didn't always exist!