Nowadays, there is a lot of focus on understanding the dynamics of different generations, be it in the workplace, housing, or social life. We hear of Baby Boomers born 1946-1964, who are known for their vocal and demanding attitude, while Generation X, born 1965-1980, are more technologically savvy than their parents. On the other hand, millennials born 1981-1996 embrace change, while Generation Z born 1997-2012 are called “screenagers” because they were born when there was widespread access to the internet and technology. Meanwhile, Generation Alpha, born 2013-2025, is expected to have immense comfort with AI. These are modern ways in which we know a generation.

But how long is a generation in the Bible?

The biblical concept of a generation varies from the modern version that we have come to know. Generally, a generation is around 38 years. However, in the time of Abraham, a generation was a hundred years. There are also cases in the Old Testament where the word generation means descendants or the spiritual condition of a group of people.

Biblical Meaning Of Generation

The word “generation” refers to a group of people descended from a common ancestor. For instance, Jacob and Isaac are descendants of Abraham, while Noah and Lamech are descendants of Methuselah. People often list a generation when they want to trace the lineage of a particular individual or group.

From Adam to Noah (the patriarch), a generation was around 100 years. After the floods, the lifespan went from 900 to 200. After the people of Israel left Egypt, they stayed in the wilderness for 40 years until all the previous generations except Caleb and Joshua had died. God also commanded that only those 20 years and above would enter the Promised Land.

So if they stayed in the desert for 40 years, a generation would be 40-60 years. In contrast, Job lived 140 years; the Bible describes that as four generations. When we divide 140 by 4, then in this context, a generation is 35 years.

Based on this analysis, it’s clear that people in the Bible died at different ages, which suggests that the concept of a generation may have differed in terms of its length. So it’s impossible to tell exactly how long a generation is.

In the Bible, the word generation has three meanings: length of time, descendants, and the spiritual condition of a person or a group.

Period/Length of Time

Generation as a period means the total number of people of approximately the same age living in a society. A good example of where we see this is in the Bible in Genesis and the Book of Job:

“After four generations, your descendants will return here to this land, for the sins of the Amorites do not yet warrant their destruction” (Genesis 15:16).

“After this, Job lived a hundred and forty years; he saw his children and their children to the fourth generation” (Job 42:16).

The word generation in some biblical contexts also refers to a time characterized by a unique event. For example:

“Thirty-eight years passed from the time we left Kadesh Barnea until we crossed the Zered Valley. By then, that entire generation of fighting men had perished from the camp, as the Lord had sworn to them” (Deuteronomy 2:14). 

This passage shows that a generation is 38 years and also points to a specific event.

Descendants

The Bible also uses the word generation to talk about people who have descended from a common ancestor.

“Thus there were fourteen generations in all from Abraham to David, fourteen from David to the exile to Babylon, and fourteen from the exile to the Messiah” (Matthew 1:17). 

Here, Matthew uses genealogy to state that Jesus has a legitimate right to claim His position as a direct descendant of both Abraham and David.

But to believe that only 14 generations have passed from Abraham to Christ is misleading. So, this version of Matthew is a partial genealogy of Christ. But it gives us a clue of Jesus’s descendants and helps us trace his lineage.

The Bible also gives us several examples of how a generation means descendants by saying: “This is the book of the generations of Adam. When God created mankind, he made them in the likeness of God” (Genesis 5:1).

Spiritual Condition

The word generation in the Bible also refers to the timeless spiritual condition of people. God talks of this timeless spiritual generation by saying: “They would not be like their ancestors- a stubborn and rebellious generation, whose hearts were not loyal to God, whose spirits were not faithful to him” (Psalm 78:8)

When talking to the scribes and Pharisees, Jesus referred to a “generation of vipers” and “an evil and adulterous generation” (Matthew 12:34-39). He also spoke of a generation that will experience a reckoning for thousands of years of sin.

“From the blood of righteous Abel to the blood of Zechariah the son of Barachiah, whom you murdered between the sanctuary and the altar. Truly I tell you, all this will come on this generation” (Matthew 23:35-36).

The fact that Jesus refers to Abel and Zechariah whom ‘you murdered’ means he does not have the actual people listening to him in mind but of a timeless generation.

Nonetheless, the accusation is also directed against the people listening to him personally, for they are of the same kind or of the same spiritual/evil generation of vipers like those who killed Abel and Zechariah. The Bible refers to the scribes and Pharisees as the “children of those who killed the prophets” (Matthew 23:31).

An Evil Generation

From Matthew, there is also a reference to ‘an evil and adulterous generation (Matthew 16:4). All these points to the notion that it is not a physical group of the age cohort that Jesus is talking about but a spiritual generation characterized by certain conduct.

People displaying this quality are also considered a timeless generation because they are God’s children from the same spiritual family. Still, they are the opposite generation to that of the serpent.

This tells us that there are two distinct generations. The first generation is the one displaying unbelief against the good news that Jesus represents and associates miracles from Christ with Satanic power. They also reject Jesus as the Messiah and glorify Satan.

A group of people that exhibits these characteristics is also called the evil and adulterous generation (Matthew 12:33-39; Luke 11:29). This generation is associated with Satan, often pictured as a serpent/viper in Scripture. They are seen as bad trees incapable of producing good fruit. The second type of generation is the one that bears the fruit of the Holy Spirit, repents, and obeys God’s will. Jesus considers this generation as part of His spiritual family (Matthew 3:7–8; Luke 8:21).

Conclusion

The length of a generation in the Bible is not explicitly defined. It varies depending on the context. For example, from Adam to Noah, a generation was approximately 100 years, while in the era of Moses, it ranged from 40 to 60 years. During Job’s time, it was around 35 years. There is also a generation that is not race-specific in principle, but a timeless one defined by spiritual connection.