And Constantinians (all kinds) should be very afraid:
Leithart’s Christ is not the Christ of Scripture. I say that not as a theological liberal who views Christ as a type of Gandhi and finds the idea of a coming Judgment to be abhorrent. I say this as a follower of Christ who understands the nature of the Spiritual Kingdom and our call to suffer as martyr-witnesses in This Age. The Triumphalism of Leithart is only to be understood in light of the Second Coming and in a context in which sin has been eradicated. A Postmillennialist like Leithart looks for the Church to bring in a millennial golden age, a Church through the force of cultural transformation to all but eradicate sin. Through culture and legislation (and presumably the Spirit) the reign of Christ will be brought to bear on This Age. Christ returns after the world has been Christianized… again a term and concept I would argue is the result of abstract philosophical commitment and speculation, not the fruit of New Testament exegesis.
I’ve always found it ironic that Calvinists, believers in Total Depravity would embrace such a vision of Christianization. I too embrace Total Depravity and believe there’s no Scriptural warrant for this view. They would argue the Spirit will effect this change. The same Spirit inspired the New Testament and provides a very different interpretation of the Old Testament than they will grant or receive and nowhere is there any suggestion that sin will in any way be diminished before Christ’s return or through the cultural efforts and/or political expressions of the Church.
Like the Dispensationalists they prioritize the Old Testament and its prophetic visions over and against the New Testament and its interpretation of them. In their systems The Old Testament interprets the New rather than vice versa. Rejecting the Apostolic hermeneutic they insist (like the Dispensationalists) that a future chiliastic kingdom is the destiny of the Church. The Dispensationalists believe this promise to be centered on Israel of the Old Covenant. The Postmillennialists rightly believe The Church is the New Israel and the inheritor of its promises but it wrongly believes that not only will the Church conquer Palestine, it will politically and culturally conquer the whole world. One camp believes the political millennium will be based on the Jews, the other on the Church but their basic assumptions are the same. They both embrace a politico-cultural doctrine of the Kingdom.
Both schools seek prophetic fulfillment apart from the Christocentric teachings of the New Testament. Both reject the New Testament’s teaching that all the Old Testament promises, types and symbols point to and find their fulfillment in Christ (2 Cor 1.20).