The Trinity Doctrine that he talks about didn't even exist until 400 years after Christ.  

"Scripture contains neither the word Trinity, nor an expressly formulated doctrine of the Trinity. Rather, according to Christian theology, it "bears witness to" the activity of a God who can only be understood in Trinitarian terms.  The doctrine did not take its definitive shape until late in the fourth century."

He acknowledges that both religions trace back to Abraham just as I stated.

His theology (not followed by Unitarians-who are also Christians-for example ) says the doctrine got going about 100 years after Christ. "Ignatius of Antioch provides early support for the Trinity around 110 AD."

https://en.wikipedia.org/wiki/Trinity