The Greek word γενεὰ (genea) is consistently translated as "generation" in Jesus's word in the NT. However, the word hss much broader meaning than that. It generally means a "race", "family", "generation", "class," and "kind." It is the root word from which we get the scientific term "genus" defining a category of life.
More importantly, Jesus seems to use this word several different ways. His meaning in any given verse is often open to interpretation. Jesus uses genea to mean:
- The human race generally,
- The Jewish people specifically,
- The specific group of people challenging him, usually the Pharisees.
It requires only a little detailed examination to see how he is using this word in a specific situation. Jesus uses the word genea in nineteen verses. We can group these uses into three categories.
Describing Types like the Pharisees
The first category are verses where he is referring to the Pharisees. This is the largest group, including eleven of the eighteen verses (Matthew 12:41, Matthew 12:42, Matthew 12:45, Matthew 16:4, Matthew 23:36, Luke 11:29, Luke 11:30, Luke 11:32, Luke 11:50, Luke 11:51, Luke 16:8, Luke 17:25). You will notice that many of these verses are close together. This is because they were spoken during the same encounter with the Pharisees. Many of these verses are also the different Gospel's versions of the same encounters where the word genea is mentioned in parallel verses.
In these verses, Jesus is answering a challenge from the Pharisees, and the Gospel writers purposefully mention the Pharisees as the target of these sayings either prior or shortly after the verse. In these cases, it is often very easy to see that Jesus means a certain type of person, specifically, those who are like the Pharisees. Jesus often goes further describing the kind of person he means. For example, they are are a wicked and unfaithful type of person (Matthew 16:4), so Jesus isn't leaving any doubt about the kind of people he means. While Jesus did deride the Pharisees by name, most famously in the Sermon on the Mount, he seems to prefer to refer to their "type" of people by genea rather than naming them specifically.
It seems unfair to translate this term as meaning his whole generation by these uses of the word. Especially since in most of these cases, the crowd seemed to be on Jesus side against those challenging him. It seems not only unlikely but somewhat absurd to this that he was branding his entire generation as wicked and unfaithful when his target is so plainly only a certain type of person.
A Specific Type of People
The next group is somewhat smaller and related to the first group. In these cases, Jesus uses genea to refer to a specific type of people that he then goes onto describe. This group includes Mark 8:38 where he describes the group as faithless and mistaken. In also includes Matthew 11:16 and Luke 7:31 where Jesus describe the type of people as those like children. In these cases, Jesus may also be describing those who are like the Pharisees but he doesn't do it in the specific context of addressing them as challengers.
Again, it doesn't seem necessary or realistic to apply or limit Jesus's genea to his particular generation when he is talking about a certain type of person.
The Entire Human Race?
it seems as though Jesus is using the term to refer to either a specific race of people, possibly his own, or, more likely, the entire human race. This verses include three parallel verses that quote more or less the same statement by Jesus in three different Gospels. These are Matthew 24:34, Mark 13:30, and Luke 21:32. This is the verse that states (Mark 13:30) "this generation shall not pass, till all these things be done."
I see no basis at all for limiting this genea to a specific generation. Since Jesus doesn't limit this to a specific type of person, however, it is hard to say who he means. However, the evidence is that he problem is referring to people like the Pharisees, that is, people who do not choose to trust in him. It could, however, refer to the whole human race.