In his book The Synoptic Problem, p. 14 (free online here), Mark Goodacre says this of reading the gospels in harmony:
“This way of reading the Gospels is not simply a recent and popular development. It is the way in which they have been read for most of their history. It proceeds in part from an embarrassment that there should be four Gospels in the Bible and not one. If we are to think of the ‘gospel truth’ and the reliability of Scripture, there might seem to be a problem in the fact that the first four books of the New Testament announce themselves as the Gospels According to [sic] Matthew, Mark, Luke, and John.”
There is something to this. Bart Ehrman has critiqued Christians who ignore the differences between the gospels saying that doing this is creating one’s own gospel, a fifth gospel. On the other hand, I know in some traditions that the canon takes precedent so that the individual gospels find greater meaning together (e.g. so that the high Christology of the Gospel of John should impact how one reads the Christology of the Synoptics).
What do you think is the benefit of reading each gospel giving attention to its separate and distinct voice and what could be the benefit of reading them together? Do we do each gospel injustice by reading them together (making a fifth gospel)? Is there a time to read the gospels together (e.g. liturgy) and a time to read them separably (e.g. historical research)?