The author of Hebrews contrasted "milk" with "strong meat."
For every one that useth milk is unskilful in the word of righteousness: for he is a babe.
But strong meat belongeth to them that are of full age, even those who by reason of use have their senses exercised to discern both good and evil.
The metaphor of "milk" represents basic things about the Gospel, ideas that need no chewing. Infants lack teeth, and so they are unable to chew, or to eat "strong meat," which is another metaphor.
In John's account of the saints who were beheaded reigning with Christ for a thousand years, the simplistic approach is to say it refers to a millennium on the earth. That view might be characterized as handling John's prophecy as if it was "milk," food meant for babes. It involves little interpretation, and difficulties are ignored. It can simply be swallowed, or believed, without chewing, or understanding.
Those who say there is to be a thousand years when Jesus reigns on the earth at Jerusalem and the Jews are exulted and doted on by Gentiles have a problem with the attack by the hordes of Gog and Magog that is supposed to come at the end of it. Isaiah wrote:
And he shall judge among the nations, and shall rebuke many people: and they shall beat their swords into plowshares, and their spears into pruninghooks: nation shall not lift up sword against nation, neither shall they learn war any more.
If they don't learn war any more, why are they all equipped with swords and clubs and spears and bows and arrows, shields and bucklers, etc., as described by Ezekiel?
When the earth is full of the knowledge of the Lord, why would Satan be let loose, to deceive the nations? What a sad end to the thousand years -- all those people deceived, who attack the beloved city!
Some say that the attack by Gog and Magog comes at the beginning of the millennium rather than its end. Others say it occurs before the millennium, and they search for signs of an invasion by Russia and Iran and various other nations. But this idea is problematic, because the Jews have built a great wall or fence around the West Bank and the prophecy says the invaders come against "a land of unwalled villages." The Jewish state of today does not qualify; besides, the idea of armies coming on horses and armed with bows and arrows and spears and clubs does not fit today's military technology very well.
Still another idea is that there are two invasions, one at the start of the millennium, one at the end. Or, one before the millennium, and one at its end. The one at the end is based on Rev. 20:8-9. The first one is based on Ezekiel 38-39.
None of these schemes is very satisfactory, and the whole idea of a rebellion in the millennium seems to contradict what Isaiah wrote, "neither shall they learn war any more" ... "They shall not hurt nor destroy in all My holy mountain."
The idea of reigning with Christ now, in this life, is revealed in Paul's epistles, Ephesians 2:6; Colossians 1:13. John also brings in the concept of beheading. Jesus spoke of cutting off a hand, and plucking out an eye; John spoke of beheading.
And if thy right eye offend thee, pluck it out, and cast it from thee: for it is profitable for thee that one of thy members should perish, and not that thy whole body should be cast into gehenna.
And if thy right hand offend thee, cut it off, and cast it from thee: for it is profitable for thee that one of thy members should perish, and not that thy whole body should be cast into gehenna.
I suggest that the meaning of beheading should be understood spiritually; it refers to the mind being renewed, "be ye transformed by the renewing of your mind;" [Romans 12:2] "be renewed in the spirit of your mind." [Ephesians 4:23] It is not that hard to connect beheading with the mind change involved in becoming a Christian. Just as beheading is personal and individual, the binding of Satan, and reigning with Christ, are concepts that are personal, and individual.