So Basically he is saying that he believes Muhammad received the Qur'an from god but he chose to remain a Christian.
To put it another way, Keith Moore is saying he believes that he will go to hell and that he is on the path of those who have earned the wrath of God BUT he chose to remain a Christian.
You definitely have to be a Muslim to believe in something as stupid as that!
Actually he is not alone there. The eminent scholar of Islam, Montgomery Watt (the guy that wrote 'Muhammad at Mecca' and 'Muhammad at Medina' back in the 1950s) also believed that Muhammad was divinely inspired but also remained a Christian.
At least that is what it says on
wikipedia.
But he also had this to say:
So much must be said in fairness to Muhammad when he is measured against the Arabs of his time. Muslims, however, claim that he is a model of conduct and character for all mankind. In so doing they present him for judgment according to the standards of enlightened world opinion.
I guess he thought Muhammad was an "unenlightened" prophet...