When Moses popped up with his whole "Let my people go!" riff he was a representative of their god (who is generally just known as 'God'; it;'s all about the capital G wth this one). The Egyptians did not discredit the existance of this deity but simply labelled It has was appropriate from their point of view; God of the Jews.
Time goes on, things change, a nice wholesome virgin girl gives birth to Jesus/Yeshua/whatever name you choose to refer to him by; the son of God (big G). For the longest time I didn't wholly buy that the Christians, as a whole, believed Jesus was actually God given flesh and not just the son of...but a post I made to that effect a couple weeks back has shown otherwise. However, this does represent a mildly odd problem when you think about it...
...least when I do.
The Jews worship God.
The Christians worship Jesus.
While it can be argued, and it is by many of them, that the Christians acknowledge that Jesus is in fact God (little g)...the Jews do not share this opinion. Seeing as it was their God (big G) first then it stands to reason they should be the authority on this.
So which way do we look here?
Jesus and God are different beings, said so by the different people that worship them. The Chrisitians can toss up that "Holy Trinity" bit as much as they like but without the faith that God originated from backing the concept (an oddly polytheistic "3 as 1" concept no matter how you slice it) then it can not be used as an irrefutable fact.