The word, ‘synoptic,’ as defined by Webster’s Dictionary has four meanings; one of which is, “presenting or taking the same or common view.” This definition references specifically the first three of the four gospels. But there can be found certain dissimilarities among the gospels. For example, how can Matthew record Jesus as having a sermon on the mount, whereas Luke records Jesus as having a sermon on the plain? Which is it? The answer is probably both.
Craig Blomberg writes in “The Historical Reliability of the Gospels” that “if one Evangelist knew that Jesus said something similar on several different occasions but had a written account of his words only from one of them, he would have felt free (and been completely justified in doing so) to follow that wording in his description of Jesus’ teaching on any of those occasions (Blomberg, 183).” Therefore, Matthew could have chosen to phrase from a sermon on the mount, whereas Luke phrased from a sermon on the plain.
Blomberg also goes into detail about how the writers could have combined several sermons together, giving the impression that they are from one complete sermon, a writing style not questioned in that day. Luke also seemed to purposely arrange the sayings of Jesus in a topical sequence. This could also account for some gospels telling sermons in a differing order than each other.
These differences might imply that the gospel writers couldn’t get their story straight, thereby giving the notion that we can’t really know the truth of the gospel. In actuality, the gospel writers used writing methods accepted for that day. That the writers did not go into detail explaining their writing style was not necessary for their audience in the same way that today’s writers do not need to explain their writing style. What can be reliable from a synoptic point of view is that what Jesus taught can be paralleled with other gospel accounts of his teachings and can be found compatible.