What does Psalm 10:12 mean?

David calls upon the Lord to act on behalf of those who are oppressed (Psalm 10:2–3). The wicked man has regarded God as non-existent (Psalm 10:4), ignorant of the wicked's evil actions, and hiding His face from evil (Psalm 10:11). David's plea here is for God to come forward like a warrior and push back against such evil people.

In a similar mood, Revelation 6 depicts tribulation martyrs crying out loudly for revenge. They ask: "O Sovereign Lord, holy and true, how long before you will judge and avenge our blood on those who dwell on the earth?" (Revelation 6:10). They are told to rest a little longer until their fellow servants and brothers were killed (Revelation 6:11). Under the sixth seal, the Lord judges everyone, even the kings, the great ones, the generals, the rich, and the powerful (Revelation 6:12–17).

God may not avenge His servants immediately, but in His good time He will avenge them dramatically and completely!