Why should anyone believe that the authors of the gospels would deny each others details? Not only is there no reason to believe that, there is reason to not believe it since they all promoted the same religion. But regardless, what you are saying is that if two witnesses to a crime don't like each other, then the judge can't consider both of their testimonies about a single crime they witnessed. But you are obviously wrong. The problem with arguing that scribes and communities altered stuff is that the biblical texts were copied with multiple lines of transmission.. they were never isolated as the Koran was at the uthmanian revision. They were copied into multiple regions into multiple languages into multiple societies and multiple continents, by every tom joe and harry who had the means to copy them. If people in the roman church corrupted it, then the churches in india established by the apostle Thomas on the malabar coast which didn't have contact with the roman church for hundreds of years would have had different gospels. They could also be compared with the manuscripts in africa, the ones in syria, turkey, etc. the corruptions would be at odds with the ante-nicean biblical quotations by the church fathers prior to canonization. and they could be compared with translations of bibles from outside of the roman church like wulfias gothic bible from around 300ad. There is no loss of the original text. Alterations, variants, and scribal errors can be seen and corrected through textual criticism because of the multiple lines of textual transmission. Even the anti-christian bible scholar bart ehrman acknowledges the tenacity of the biblical text as better than any other work of ancient history; tenacity is the ability of the transmitted text to retain the original content despite copying, isolated corruption and variants. you have no argument here.