Where did you come up with the belief that the age of accountability is 20?

The age of accountability is a Biblical concept. There has to be some point when Yahweh decides that a young person is mature enough to be held responsible for his or her actions. From Yahweh’s dealing with Israel that age is 20. Note:

• A person was considered an adult in Israel by age 20, Num. 14:29; 32:11.
  · At the age of 20 a person was considered worthy to serve in the temple, Ezra 3:8, Lev. 27:3.
  · A man was old enough to fight in war by age 20, Num. 26:2.
  · The cut-off age to be considered an adult in the census was 20, Num. 1:3.
  · The age of Levites who served in the temple was lowered to 20, 1Chron. 23:24.
  · Those who were 20 and older had to pay ½ shekel atonement offering, Ex. 30:14.
  · No one 20 years of age and older was allowed into the Promised Land except for Joshua and Caleb, Num. 32:11. This shows that Yahweh did not hold those under 20 accountable for the sins that kept the adults barred from the land that represented salvation. Generally, adolescents do not have a complete grasp of the consequences of sin. This also shows that baptism should not take place among children, who have not matured enough to fully realize the seriousness of repentance and a changed life.

Each of these shows a pattern — that age 20 is the time one entered adulthood and had adult responsibilities extending into the realm of worship. That does not mean that a young person age 19 is not mature in thinking, nor does it guarantee that a person older than 20 is mature, either. But no other age in Scripture has so many indicators showing that Yahweh considers it a key milestone in one’s entering into responsible maturity, and the age when He considers one spiritually mature enough to be held accountable for what one does. This, of course, is no license for anyone less than 20 to be profligate and live sinfully.

If one had to be 20 to serve in the spiritual function of temple worship, it is a key age as well when it comes to one’s spiritual attitude toward serving Yahweh. Could this Scriptural precept be the reason our society considers 21 to be the age of adulthood?