score:7
One witness is not enough to convict anyone accused of any crime or offense they may have committed. A matter must be established by the testimony of two or three witnesses.
The above verse is a biblical basis to understand a reason for the different gospels. Also the three first gospels were written with different audience in mind:
Matthew wrote with Jews in mind, in Hebraic with Eusebius, Origen and scholar Jerome to testify this.
Mark wrote with non-Jews in mind. For example Latin terms are used, contains explanations that would not have been necessary for Jewish readers and also explain Semitic terms.
Luke wrote it for Theophilus (Luke 1:1-3)
John provide more information for events that the other Evangelizers don't say something.