Revelation 20 & Universalism

I know you are busy, but could you take just a brief moment and fill me in on
  • [Part A] how you view the Rev. 20 passage and
  • [Part B] how a wrong view there can open the door to universalism.
Being slow of mind, it will help me to get up to speed. So thanks so much for doing this. Don't take a lot of time, just a brief response. ~WH
 
The above is a reasonable 2-part question. What follows is my 2-part answer.
 
[Part A] How I view the Rev 20 passage can be found at: LINK
 
[Part B] How the wrong view Rev 20, "Rev 20 was all fulfilled by 70 AD," leads to Universalism:
  1.    Revelation 20:4 describes the coming to life of the souls of those slain for their witness for Jesus and for rejecting the mark of the Beast. This is the first of two groups of souls resurrected from the dead in Rev 20:4-6. Since the participants of this first resurrection are declared blessed and holy, we may justly call this, "The Blessed & Holy Resurrection." Its participants are rewarded by reigning with Christ for a thousand years and are granted immunity from the anticipated Second Death.
  2.    Revelation 20:5 describes the coming to life of "the rest of the dead" at the end of the thousand years. We may call this, "The Resurrection of the Rest of the Dead."
  3.    Whether one understands the term "thousand years" to mean 1000 years, 1000 hours, or a 1000 seconds, it is still describing a span of time with the aforementioned events marking its starting and ending points.
  4.    When this span of time is made to terminate at 70AD, the starting point is made to be some time before the disappearance of the New Testament writers. This forces the Blessed & Holy Resurrection (Rev 20:4) to become an experience already available to the New Testament writers while yet in their mortal-natural bodies of flesh, (error of Hymenaeus, 2 Timothy 2:18). To accommodate this, the "come to life" of Revelation 20:4 is made to mean "come to covenant life."
  5.    Someone who buys into point 4) then reads Revelation 20:5a and sees that "the Rest of the Dead" eventually "came to covenant life" with the same grammar and vocabulary by which the Blessed & Holy of Revelation 20:4 "come to covenant life" a thousand years earlier.
  6.    He concludes, then, that whether one dies as a Blessed & Holy witness for Jesus (Rev 20:4) or as the Rest of the Dead (Rev 20:5), his final stance with God is the same: he still "comes to covenant life." That belief is commonly known as Universalism.
Summary: "Full" Preterism (Covenant Eschatology) interprets the word "covenant" into the Text of Rev 20:4-6 to make the Blessed & Holy Resurrection (first resurrection, Rev 20:4) precede Christ's Return by decades so that the Resurrection of the Rest of the Dead (Rev 20:5a) may occur at the moment of Christ's Return. Consistently applied, this addition to the Text forms the basis for "Full" Preterist Universalism.

Revelation 20:4-5 ~foreseen around 63AD in the predictive vision given to the exiled Apostle John of "things shortly to come to pass," Rev 1:1 & Rev 4:1
And I foresaw thrones, and they sat upon them, and judgment was given to them. And I foresaw the souls of those who had been beheaded because of the testimony of Jesus and because of the word of God, and those who had not worshiped the beast or his image, and had not received the mark upon their forehead and upon their hand; and they came to convenantal life and reigned with Christ for a thousand years. 5 The rest of the dead did not come to convenantal life until the thousand years were completed.
NASB