As a matter of fact, those who received the older scriptures did not dispute about the message when it was revealed to them (it happened later when they started to tamper with the scriptures)
Faridul Haque
Nor did the People of the Book(s) get divided until after the clear proof came to them
Hasan Al-Fatih Qaribullah
Those to whom the Book was given did not divide themselves until the Clear Proof came to them
These People of the Book did not dissent amongst themselves (with regard to believing in the Prophethood and Messengership of the Last Messenger and recognizing his holy status), until after the clear proof (of the Prophethood of Muhammad [blessings and peace be upon him]) had come to them. (Then, they broke up: some of them accepted belief in him whilst others became deniers and disbelievers out of jealousy,
And the people of the Scripture (Jews and Christians) differed not until after there came to them clear evidence. (i.e. Prophet Muhammad (Peace be upon him) and whatever was revealed to him)