After a flirtation with post-millennialism over the last several months, I think I'm finding my way back to the a-millennial fold, though with some post-mil clarifications/revisions/tendencies, perhaps.
Here's the skinny:
Both views say we're living in the millennium now, and that it won't be a literal 1,000 years.
Post-mil says Scripture requires we be optimistic about the end times, since Christ will redeem and preserve His own to the end. All the evil Satan can unleash can't prevent that. I have come to believe this, regardless of whether a-mil tends against it, which is post-mil's charge against a-mil. I don't think this charge is necessarily, true, nor that optimism is the possession of any one millennial view.
I am an end times optimist.
But there's more to the story than optimism/faith.
Post-mil also says that more will be evangelized, and culture will become more Christian, through time and prior to Christ's 2nd coming. This is based on Scriptures like Ps 2:8; Isa 2:4; 11:9; Jer 31:34. As an example: “The earth will be as full of the knowledge of the Lord as the waters cover the sea, and the whole earth will be full of His glory.” I believe these Scriptures can just as easily apply to the new heavens and the new earth, following Christ's 2nd coming, as they can before it. At least, we cannot say that it must apply before.
Greg Bahnsen, the late and noted post-mil man, argues that Christ is reigning in heaven, waiting for God to subdue His enemies under His feet. I agree. Where the disagreement comes in is what will happen when Christ returns. Will there be some conquering left to do, or not? It seems Rev 20 shows the conquering of the Son of God, going forth to war, not an inauguration speech.
Now, perhaps Armageddon could co-exist with the nations being “thoroughly Christianized,” as one writer puts it. But it seems more likely to me that the widespread opposition to Jesus at the end is not just a last-minute changing of the mind of all the nations, based on Satan’s deception. Does it make sense to think of the nations thoroughly Christianized, and then all those nations gathering to make war against Jesus? Bahnsen says if Satan deceived them, they must have been Christianized before, but this isn’t necessarily true, either. Most unbelievers today (in OUR country, that is) don’t pour forth effort into destroying the Church or her Lord, but if Satan deceives them, they might. The deception might not be from good to bad, but from bad to worse.
So, once again, the post-mil picture of the end isn’t necessitated by Scripture, although it is one possible scenario.
Reformed folk are strong on the already-not yet tension in the nature of Christ’s Kingdom. It is already here, but not yet fully implemented. The question is, will we be 99% already the day before Jesus comes back (post-mil, it seems to me), or 75%, or 50%, or 20%? And is this something we can know from Scripture? And does faith require us to expect a certain number? On this question, I’m still studying the various applicable texts, with no present conclusion.
My concern is the rhetoric that if you aren't post-mil, you aren't applying your faith to the end times, or to church life today. I do believe the gates of hell won't prevail against the attack of the church, but throughout Scripture, God usually insists on fighting FOR His people, while we sing Psalms and worship Him (Exodus 15; 2 Chronicles 20:1-30).
I do believe that we are called to be part of the attack on hell's gates, tearing down the strongholds of this world, demolishing arguments, living the light of the world so they can't gainsay the Gospel, and all that. But in the end, only God can change hearts, only He can conquer spiritual strongholds. He may use us to accomplish much of His mission before He returns; He may finish the job at His return.