Related to the concept that covenants can have invisible aspects is the whole concept of Two Realms. Heiser is obviously aware of this, having written Unseen Realm, and refers to it often enough, but he lacks the broad sweep of how the Spirit Realm does and does not relate to our Fallen Realm.
I’m not faulting him; it’s not his kind of subject. Rather, I’m noting that his discussion of eschatology lacks a few things that matter very much to us. This is why his characterization of Amillennialism doesn’t include our perspective.
He’s on the right track using the theological concept of “already-but-not-yet” — that a thing in the Bible is connected to both realms, and that something asserted true about our situation as believers can apply partially now and more completely in Eternity. This reflects the nature of divine revelation, often expecting us to grasp things on two levels at once. It’s just that Heiser doesn’t seem to apply it often enough.
One place where he seems to make an error is the nature of Divine Election. He’s dismissive of most mentions of it, because he assumes it is limited to just this realm. So far as I can tell from his teaching, he doesn’t see election as something that has somewhat different effects on both levels.
He knows that the word “angels” means different things in the OT versus the NT because of how the Hebrew language gets translated into Greek and English. But he doesn’t see how that applies to Election. The Chosen Nation (AKA “Elect Nation”) is one thing, as is the issue with Paul’s discussion of Jacob and Esau, or Pharaoh as “chosen”. But the Eternal Elect souls are another thing entirely.
This is why you need to pay attention to the applicable covenant for a proper context on the use of the terms “chosen” or “elect”. What can we know about the covenant purpose in the context under discussion? Jacob and Esau were under Abraham’s Covenant. Pharaoh ran up against the Covenant of Moses. What happens with election under the Covenant of Christ? The covenant’s purpose is the key to what we are to make of election.
Election is simply God’s prerogative applied to the context. We can predict some outcomes simply from knowing which covenant is in force. He always acts with a purpose, and it was Heiser who revealed the business of God having a dispute with the Devil and some members of the Divine Council, and that the whole purpose of God in creating humans rests partly on our ability to side with God against His troublemakers.
While we are limited in grasping all the implications of that image, it explains why election under Christ means “going to Heaven” unconditionally, or at least as far as we are permitted to see. The conditionality element shows up in our lives here; it’s the Covenant of Christ. It was Heiser who noted that this was a secret kept from the Divine Council and Satan, that God would elect souls from every nation to His eternal kingdom in Christ, and ignore the national boundaries.
You should bring these assumptions with you when examining the passages that seem to address the Second Coming and the End of Time.