Postmillenialism is my favourite brand of eschatology. If I could choose one of the options to be true (i.e. amill, classical premill, dispie premill, preterist postmill, classical postmill) I'd choose the postmillenial option. In short, and at the risk of charicature, the postmillenial position on eschatology teaches that the gospel will conquer the world to the extent that the knowledge of God will cover the earth as the waters cover the sea BEFORE the Lord returns. The church will succeed in converting the world and then Christ will return to 'take over the reigns'.
You've got to love such a position. As well as having a reformed heritage, I can't help but see the benefit in it stimulating hopeful evangelism. Knowing that the gospel is going to conquer the world, no matter what resistance one may face, should instil an iron spirit in even the most timid evangelist. Nevertheless, despite it's obvious attractions, the big question remains, i.e. is postmillenialism biblical?
I read Psalm 110 the other day. Verses 5-10 speak of the eschatological judgement wrought by God's warrior king:
The Lord is at your right hand; he will shatter kings on the day of his wrath. He will execute judgment among the nations, filling them with corpses; he will shatter chiefs over the wide earth. He will drink from the brook by the way; therefore he will lift up his head. (ESV)
The obvious question is, if the gospel is going to have such a far reaching impact on the earth then why is Christ returning to judge? I know the pat answer, 'while righteousness flourishes, evil will also flourish and Christ will return to destroy his last enemies.' Still this doesn't make sense within the postmill framework. Like I said, if the gospel is to have such a far reaching impact on the earth, why does his judgement still require that he 'fills the nations with corpses' and that he 'shatter chiefs over the wide earth'?