Concerning the Millennial Kingdom, Satan's dominion in Time, Why?

Concerning the Millennial Kingdom and those who deny what the Holy Spirit has said...

Messiah's Kingdom has NOT been established upon this Earth at this time but this Earth is currently under the sway of the Devil (2 Corinthians 4:4) and will remain so until Messiah's 2nd-Advent and the establishment of His Millennial Kingdom where the Evil One is bound for 1000-years.

All things have been given-over into the hands of the Son concerning the Father's eschatological will (John 3:35) but the Evil One's dominion in Time is part of the Father's eschatological plan in that Satan is currently used as a sifter dividing wheat from chaff; sheep from goats; righteous from unrighteous, and this sifting will continue until the fullness of the Gentiles has come to fruition (Romans 11:25). At the conclusion of the Millennial Kingdom the Evil One will be released to deceive the nations once again and our Lord will destroy His enemies via His omnipotent power.

Where you lack understanding is the reasoning for the Millennial Kingdom which provides Messiah the Kingdom denied Him at His first advent but more importantly, the Millennial Kingdom is an "object lesson" as it provides a stark differentiation between the previous 6000-years of horror that resulted from the Evil One running amuck and the 1000-years of complete peace while the Evil One is confined; this differentiation between good and evil provides undeniable proof to the faithful angelic creation that their former boss, an anointed but rebellious cherub angel, is indeed the culprit for all horror and sin and he does deserve punishment in Hell forever (Rev 20:10) and the angelic creation will see and affirm that Father was correct and righteous in extricating the rebellious angels from the Kingdom (Luke 10:18) and it will be abundantly clear that the Father's way is the ONLY way to peace with permanence and the object lesson of the Millennial Kingdom will act as a bulwark against future rebellion in the New Jerusalem where free will remains extant by necessity; all of this, while the Father maintains volitional love with His angelic creation through defeating the Evil One via selfless love (1 John 3:8b; John 3:16). All praise and glory will be focused upon the Father, Son and Spirit.

Messiah's Millennial Reign does NOT culminate in failure but in eschatological fulfillment for cause. I don't adhere to any sense of dispensationalism...I tell you what the Holy Spirit tells me and you're free to listen or deny.