Gideon made the ephod from the gold of victory and placed it in Ophrah. What happens next is often misunderstood in many commentaries. The text is often read as if Gideon had seduced the people into a form of worship forbidden by God, thereby breaking the second commandment (Ex. 20:4–5), comparable to the golden calf in the desert.
Judges 8
27 And Gideon made it into an ephod and put it in his city, in Ophrah. And all Israel committed fornication with it. And it became a snare to Gideon and to his household.
fornication
Many readers approach this verse with an ethical lens, as if Gideon did something wrong. However, the text does not state that his actions were wrong; it was Israel who committed fornication with the ephod. This is comparable to the bronze serpent, which Moses made at God’s command (Num. 21:8–9): whoever looked upon the serpent was saved.
Idolatry
The bronze serpent foreshadows Christ (John 3:14), but Israel began to worship the object itself rather than its Maker (2 Kings 18:4). In the same way, the ephod, like the bronze serpent later in the days of Hezekiah, had become an object of worship.
In the Bible, prostitution is synonymous with following other gods (Ezek. 23:30; Hosea 1:2). Israel misunderstood the meaning of the ephod and committed prostitution with it, thus losing its original purpose.
Trap
Gideon did something that caused Israel to fall. He made a priestly garment, and because of it, Israel stumbled and fell into idolatry. It speaks of the Lord Jesus Christ, who after His resurrection became High Priest and hid in the heavenly sanctuary (Heb. 9:12,24). The house of Israel does not believe in Him, and this has become a snare for them.
Romans 9
32 (…) They stumbled over the stumbling stone,
33 as it is written: “Behold, I lay in Zion a stumbling stone and a rock of snare, and whoever believes in him will not be put to shame.”