Ans.01. Reading and writing were not required to modify Judaism to suit his own whims. It is all "do overs", each successive group changed that which was there, to what they chose it to be.
02. That still has not changed, there are still those who would claim Islam the vengeful and violent, as a religion of peace. Which it may be, but only if you are willing to capitulate to anothers will. In other words, bend over, and take it!
01. If some one who is unable to even read and write and has no earthly teacher could "modify" Jewish and Christian religion and pinpoint the mistakes from which they deviated from the true path .it is really strange. And if our prophet could do it, what prevented other people in Makkah doing the same?
02. People might claim any thing they wish, there are 1.5 Billion Muslims in the world who believe in the truth and sincerity of the prophet.
So far no new major religion has come up in world in past 1400 years, let us see how many new religions come in the life left for this earth before the End of Time comes!!