2. Repetitions in Luke
Luke's gospel appears to repeat several incidents or sayings, and these repetitions are often used to suggest that the Evangelist did not know which of two accounts he had available to him was true, so he inserted both of them in his gospel.
For example, Luke records Jesus taught that his disciples needed to take up their crosses and carry them in two places in his gospel. In Luke 9:23 we read Jesus said "Whoever wants to be my disciple must deny themselves and take up their cross daily and follow me" while in Luke 14:27 he says "whoever does not carry their cross and follow me, cannot be my disciple." In the same way, in Luke 9:24 Jesus says, "whoever wants to save their life will lose it, but whoever loses their life for me will save it" while in Luke 17:33 he says, "Whoever tries to keep their life will lose it, and whoever loses their life will preserve it." Repetitions With Purpose The first thing we should notice about these supposed "repetitions" is that none of them is identical with any other one. In every case the wording is slightly different although the thought being conveyed is clearly the same. The simplest explanation for this is that Jesus likely often taught the same things in different locations as he went through the villages of Galilee and Judea, and that Luke was aware not of conflicting accounts – but of complementary accounts of things said on different occasions.
That this is the case can be seen quite clearly in examples where the context of what is said is very different. Luke records that Jesus taught "all those who exalt themselves will be humbled, and those who humble themselves will be exalted" relative to guests choosing the most important seats at a banquet he attended (Luke 14:11); while he also records that Jesus said "all those who exalt themselves will be humbled, and those who humble themselves will be exalted"
(Luke 18:14) as the moral of his parable of the self-righteous Pharisee and the repentant tax collector given on a different occasion.
Once we understand this simple answer to the so-called repetitions in Luke's gospel we realize that he may well have purposely recorded multiple instances where Jesus taught essentially the same thing so Luke could show things that Jesus emphasized and repeated in his teaching (Matthew 13:52). That Was Then – This Is Different The principle also helps us understand the often commented-upon difference between Jesus' Sermon on the Mount in Matthew's gospel (Matthew 5–7) and in Luke's (Luke 6:20-49). In this instance the differences are so obvious that Luke's version is often called the "Sermon on the Plain." It is possible to understand the two accounts as recording different aspects of the same event: that Jesus first went up a mountain and sat to teach his disciples (Matthew 5:1), and then came down and stood to teach a condensed version of the same message to the crowds at the foot of the mountain (Luke 6:17).
However, it is perhaps more likely that the two accounts record two different events where the same sermon was preached in different locations with a number of differences in what was said in each. If we look carefully, we see that the audience in Matthew's account apparently came from different places than the audience in Luke's account (compare Matthew 4:25 with Luke 6:17) and this strengthens the possibility that two events, in different locations, were involved.
Putting this all together, we see that it is more than likely that the so-called repetitions in the Gospel of Luke are often no more than accounts of similar teachings given at different times and in different locations. As a skilled historian, Luke researched and handled his sources carefully (Luke 1:3), and his care in correctly situating the various events and helping us see which teachings Jesus repeated and emphasized adds greatly to the value of his gospel.