Mankind was [once] one nation, so God despatched prophets as heralds and warners. He sent the Book down along with them to bring the Truth, so as to decide among mankind concerning whatever they had been disagreeing about. However only those to whom it was given disagreed about it out of envy towards one another, after explanations had been brought them. By His permission God has guided those who believe to any Truth they may have disagreed about. God guides anyone He wishes to a Straight Road.