-Postmil simply stated says the return of Christ is after(post) the millennium. 
-Preterist Postmils(majority) will say that the millennium began in the 1st century. Historicist Postmil(minority) will say it is not yet, but either way it must come first before Christ comes back. 
-Postmil believes in an earthly millennial reign just as Premils believe, not a heavenly intermediate state when you die as Amils believe. 
-Postmil believes in one general resurrection at Christ’s return, followed by the final judgment, followed by the new earth.
-Postmil believes in a mass conversion of the world to Christ prior to his return. In other words, the kingdom in inaugurated in the 1st century, and will be consummated just prior to the return of Christ. 
-Postmil is not looking for the return of Christ at this time. They are focused on consummating the kingdom here on earth. 

Postmil has re-emerged popularity in the 20th century. But instead of wading through the tangled web of mixed beliefs within Postmil, let’s just address why NONE of them are true. 

The Presuppositional Argument - This is my favorite because it cuts straight to the crux of the matter. Postmil presupposes at least 1 of 2 things to be true in order to be a CONSISTENT Postmil TODAY. Today, in order to be consistent, you MUST either be a Calvinist or a charismatic, or both. I am neither, therefore I am disqualified to consistently hold to a Postmil position today. I say “consistent” because there is always an extremely small minority that will say they are an exception. And that’s fine they can say they are Postmil, but they don’t hold a consistent view. I say “today” because some of the reformers held to Postmil and fit outside this profile. But that was a different set of circumstances back in the 16th and 17th century that no longer exists today. The reformers were full of hope as they pulled away from the Roman Catholic Church. They believed that their movement, if successful, would bring in the millennium. But their success was only partial, and was not complete. Today that momentum no longer exists and if anything we are going in the opposite direction. 

Why is the presuppositional argument effective? - Because when you dive into the various differences between the different views of eschatology(ie. Postmil, Premil, Amil), all views make a biblical case for their view. The problem is that we are biased and favor our view and often times demand that it is the only possible understanding of a particular verse. I think it is important to understand that biblical texts can be read with different understandings depending on the presuppositions we bring to the text. The key is in making sure our presuppositions are correct. If we declare our understanding of a text as the only possible one, we are being shortsighted and biased. Yes some answers to objections are stronger than others, but we have to pick and choose our battles to only the ones we know we can win. 

The Calvinist camp - If Calvinism were true, which I don’t believe it is, they can at least make a biblical case for Postmil. And when I say “biblical case,” I don’t necessarily mean a strong one, but they can account for all verses in some way to consistently hold a Postmil position. This camp believes that the sovereignty of God(their definition of it) will consummate the kingdom of God on earth despite the lack of momentum in that direction in our world today. They are Monergists rather than Synergists. So God does not need to contend with the free will of man since they do not have free will. If man does have free will, then there lacks any kind of path for mankind to reverse course and successfully consummate the kingdom prior to Christ’s return. That is unless, you belong to the next camp who espouse the continuation of spiritual gifts. 

The Charismatic camp - This camp can also include Calvinists, so Calvinists will make up a big part of the overall Postmil camp. But charismatics, or those that believe in the continuation of the spiritual gifts, can be of Arminian persuasion and still be Postmil. The spiritual gifts such as speaking in tongues, gift of healing, or prophecy is seen as evidence that we are in the millennium today. These gifts can be increased in power by God to convert the masses and consummate the kingdom prior to Christ returning. So they also can make a biblical case for Postmil with a consistent understanding of how the masses can be converted to Christ before he returns despite there being momentum in the opposite direction.

The Dangers of Postmil - Not every strand of Postmil belief is scary. Some of it is relatively harmless, but some is very dangerous. You have what is called Dominionism. Other names associated with this is Reconstructionism or Theonomy. These will 100% come from the reformed or Calvinist camps. It teaches that the millennium will be achieved by a political movement in which Christians will establish themselves in all areas of leadership in government and society. This infiltration from within will accomplish bringing in the kingdom of God on earth, the millennium. Or it will bring the kingdom of God to its consummation. Then Jesus will come back. Many hold to a hope of what is called theonomy or theocracy, which is a government run by Christians in which the law of God is imposed on society. This is an admirable goal as even in the Premil view, a government of God is established in the earth to rule with God’s law implemented to bring freedom and prosperity to the world. The difference in the Premil view, is that Jesus will have come back and this law will be implemented properly. The Postmil view has Jesus in heaven still. So while they claim to rule in God’s name, this is actually quite scary as many cults and false religious tyrannies have claimed the backing of God, but has only resulted in disaster. To be fair, there are nuanced views within this camp and some are very fanatical and some aren’t as bad. But you have to be a Calvinist to be in this camp because it necessitates God making it happen. Today

Either way, the Charismatic Movement and reformed Dominionism are both errors that can not lead to truth. These positions are refuted on the following pages on this site: Cessation Of Healing And TonguesSeparation Of Church And State, and Nowhere Else To Run. Now there are exceptions, not every Postmil believer fits perfectly in these 2 camps. Not every Postmil believer is a hardcore theonomist that wants to implement their false version of God’s law onto society. There are certainly some very dangerous paths a Postmil view can take you down.

Postmil also believes in one resurrection versus two. An argument can be made on both sides of this. Both sides can accuse the other of bias in their interpretation. So let’s instead see which aligns with the rest of scripture so as to allow scripture to interpret scripture. Also it is worth noting that very few Postmil will be futurists of any kind because it’s not really a consistent position to simultaneously hold to both views. They primarily will be Preterists or Historicists.