Mark 1.16-20:
Passing alongside the Sea of Galilee, he saw Simon and Andrew the brother of Simon casting a net into the sea, for they were fishermen. (17) And Jesus said to them, “Follow me, and I will make you become fishers of men.” (18) And immediately they left their nets and followed him. (19) And going on a little farther, he saw James the son of Zebedee and John his brother, who were in their boat mending the nets. (20) And immediately he called them, and they left their father Zebedee in the boat with the hired servants and followed him. (ESV)
If your compare the verses above to the verses of Luke 5.1-11, you will find differences. A different setting. A different sequence of events leading up to the disciples leaving their fishing businesses. Additional insights and information about the actions and conversation between Jesus and Peter. Many theologians would say this is an example of what they have defined as the “synoptic problem”, which means that many variations are observed between and among the three synoptic gospels of Matthew, Mark, and Luke. For me, this is not a problem, but rather it makes the witness and testimony of the gospels even more certain and truly to be believed. I personally do not spend much thought trying to understand these apparent variations. Witnesses had different vantage points. Didn’t see all of what others saw and heard. The gospel writers may have had theological points to be made which were different than the other gospel writers. Or perhaps the gospel writers abbreviated the narrative in some cases, as compared to the other accounts. Or even still the writers may have chosen to write in some cases what has been called “interpreted history”.
Whatever the case, I do seek to harmonize the gospels as fully as I can, trusting that all of them are fully and completely true, and knowing that my perspective and vantage point is very limited. With all of that being said, I think the “synoptic problem” is wonderful. I view all of these accounts as what they truly are: testimony which has been compiled from eye witnesses to the events. And when you have multiple eye witnesses, what is the nature and character of their testimonies? They will have subtle differences, and maybe not so subtle, as to what each witness saw and heard. If the testimony is too perfectly harmonized, too identical, then it calls the testimony into question. I say this with the understanding that the gospel writers utilized many of the same written sources as they put their accounts together.
But the testimony of the gospels has not been contrived and forced to fit together in a perfect bundle. The gospels are a collection of many witness sources that fit together in a profound, completely believable way. And what do they ultimately tell us? That Jesus Christ was crucified for forgiveness of sin, and He was raised from the dead. The most important testimony each of us will ever receive.