We could apply this to your religion from the Jewish POV.
why a new set of spiritual thoughts?
The 'New Testament' is considered this from the Jewish POV.
Why would God inspire a book exclusively for the Arabic Nations, and discourage translations ?
There is a minor fast day in Judaism for the day the Torah was translated into Greek. English translations aren't great, either.
Why a "new God" presumably called "Allah", when in reality it's not his name, but means God in Arabic ?
'Allah' means God the same way 'God' means 'God' in English. It's the same. There's no difference. How about Christians praying to the man they believe is the Mashiach? Why a new god?
How can a believer follow the creed (shahadah) "no God but Allah...", since praying "no God but God" makes no sense.
How about the Christians' Apostles' Creed and Nicene Creed? They make no sense according to Jewish belief.
How does constant repetition of this creed make it more understandable ? (5 daily prayer towards Mecca (salat)).
It's about the prayer. There's repetition in every religious service you will go to. It's about knowing what you believe and drumming it into yourself. I've listed two of Christianity's repeated creeds above.
What are the scriptural credentials for a "new prophet" called Muhammad ?
What are the scriptural credentials for a 'messiah' that is a human sacrifice?
Is claiming to have a confrontation with an Angel or is having an ideitic memory enough credential to start a religion ?
Is having a visitation from an angel on one's way to Damascus enough credential to be considered an apostle, especially given the two differing accounts of it?
Can Muhammad claim the support of hundreds of prophecies dating back hundreds of years prophesying his arrival as was the case with Christ ?
There aren't hundreds of messianic prophecies and Jesus fulfilled none. So yes, what are his credentials?
Is his authority higher than the one given to the son of God?
In Judaism, there is no such 'Son of God' concept as one finds in Christianity, so we go back to your first question.
First cast the beam out of thine own eye;
and then shalt thou see clearly to cast the mote out of thy brother's eye.
Hi Rival,
It's a straight forward creed: There is no God but [the one] God.
The problem is that it's only straightforward when we don't think about it.
For instance: we can only say there is "no King but the King" if there were only one King in the world, because then we would know who we're talking about.
as soon as there is more than one King we are obligated to specify what King we are talking about.
eg. "there is no King but Solomon". "there is no Pharaoh but Amenhotep" God, Allah, King and Pharaoh are titles.
The sentence "there is no "title" but "title" goes against common sense, logic and even plain grammar.
It should be "there is no "Allah" but "a personal name".
To sum it up there are many Gods, Allah's, Kings, Pharaohs etc...
But there is only one Jehovah, Jesus, Solomon, Amenhotep etc...
The same goes for the Nicene Creed, it makes no sense not only to the Jews but to any rational thinking person.
As for the Apostles Creed I have to admit ignorance.
Christendom does many things contrary to Christ's teaching, Repetition in praying is one of them.
What are the scriptural credentials for a 'messiah' that is a human sacrifice?
The Prophecies.
Is having a visitation from an angel on one's way to Damascus enough credential to be considered an apostle?
You are right, it's not. That's why the disciples were very suspicious. It's what happened afterwards that's important.
The point is the Angel's appearance only made a difference to Saul not the disciples.
The Messiah's credentials are the prophecies regarding his arrival, this including the time of his birth. Subsequently the miracles he performed and fulfilling prophecies.
Judaism, there is no such 'Son of God' concept as one finds in Christianity,
Actually there is: Job 1:6 "...The sons of the true God entered to take their station...)
The bible states that Jesus is God's firstborn creation (son) and came to earth to instruct mankind in "all we need".
If we accept that, why would we need another lower ranking prophet restricted to one nation and one language?