What does Judges 17:12 mean?

Micah is living the goal of so many who want to be "spiritual, but not religious." Or those who like the general idea of religion, but don't appreciate the restrictions and limitations of a particular faith. Micah selected gods and sacred objects from various religions and constructed a shrine in his home. As an Israelite, he has forgotten or openly defied most of the basic commands of Yahweh given through Moses (Exodus 20:1–17).

Now he has hired his own priest, an actual member of the priestly tribe of the Levites (Numbers 3:5–10). Rather than being satisfied with the young man's status as a Levite, however, Micah "ordains" him into his customized religion, which is now complete. He has a system of belief and practice which suits him, even if it's spiritually incoherent. He even has a priest to officiate over it.

The following verse will show that Micah holds no hostility towards the One True God. He's not actively opposing God in the same way as some of Israel's national enemies (Judges 6:31). Instead, he's acting in some combination of ignorance and self-delusion about what God wants from him. Such ignorance is exactly what someone raised as a Levite in Israel should have been able to help with. Instead, the young Levite is also ignorant of God's commands or unwilling to give up a comfortable career to stand on principle. Both attitudes exemplify the careless, selfish spirituality of Israel at the end of the era of the judges (Judges 17:6).