The refrain in the book of Judges is that the people did what was evil in the sight of the LORD, meaning that they served other gods (Judg. 2:11; 3:7). This is how the story of Gideon begins (6:1) and how it ends (8:27, 33).
Judges 8
28 Midian was subdued before the sons of Israel, and they no longer lifted up their heads. And the land had rest for forty years in the days of Gideon.
29 Jerubbaal the son of Joash went and dwelt in his house.
30 Gideon had seventy sons who went out from his loins, for he had many wives.
31 And his concubine who was in Shechem also bore him a son, whom he named Abimelech.
40 Years
The period of forty years is mentioned four times in Judges (3:11; 5:31; 8:28; 13:1). It refers to Israel’s time in the wilderness, which also lasted forty years. This period symbolizes the people’s unbelief (Heb. 3:17-19). The contrast between forty years of rest (3:11; 5:31; 8:28) and forty years of oppression (13:1) is noteworthy. The mentioned rest is very relative, because in all cases, immediately after this period, it is stated that Israel again did what was evil in the sight of the LORD. In the story of Gideon, we read even before the forty years of rest are mentioned that the people committed harlotry (8:27).
withdrawn
In verse 29, it says that Jerubbaal went. Most translations render this as: “he went to live in his house.” However, the verb “went” comes first in the sentence and is therefore emphasized. Literally, it says: “And he went, Jerubbaal son of Joash, and he lived in his house.” Gideon withdrew, just as the Lord withdrew to heaven because of Israel’s unbelief.
70 sons
Gideon is said to have seventy sons, “born from his loins,” the biblical way of indicating that they descended from him. The number seventy represents the nations. Genesis 10 provides a list known as the “table of nations,” listing seventy patriarchs of the nations. Gideon’s seventy sons thus represent the present time, when Israel is in unbelief, while there is new life—fertility—among the nations.
my father is king
Gideon names his son Abimelech, which means: my father is king. With this, Gideon is effectively saying: I am not king, but God is king. This is comparable to the present time, when the Kingdom of Christ is not yet manifest and He is not yet visibly ruling.