I want to make one thing perfectly clear that there is only one God.
Theres no muslim god or Christan god or Jewish God. There is one God, full stop.
As for the differences Judism and Islam have many issues that are similar as for Christans this was not a seperate group from the Judism and in fact they were seen as a sect of itself.
It was only later was they were paganised like worshipping on Sun- day the day of the sun which is in line with the sun diety Baal. Who was believed to be the son of the sun - who was sacrificed for the sins of mankind. sound familiar?
Or you could look at Mithras which was someone who called the lamb of god sent to remove the sins of the world. Sound familiar? Yes of course. He was a son of god, as well, sent to remove the sins of the world.
Even if you refuse this then you must at least except that the son of god theroy has root in paganism. Which was then taken on by paul and added to the belief.
There was a history docu on television a while back and a historain was suprised about the pagan images which had then been copied into christan theology.
As for the proof of the trinity its clear from clear verses that this contridicts the ten commandments. And if you are trying to refute this then you are trying to refute your own bible.