After having caused the defection of both Adam and Eve in the Garden of Eden (Gen 3:1-6), Satan (meaning "resisitor") had no time agenda. The beginning of mankind (Adam was created in 4026 B.C.E.) was just now at the horizon. Satan took no note of God's timetable and of his eternal purpose, feeling "footloose and fancy free".
He became the first rebel and liar, followed by his adherents, Adam and Eve. Over the course of over 6000 years of human history, Satan has had control of the "world", the majority of mankind alienated from God.(John 14:30) The apostle Paul called Satan "the god of this system of things (that) has blinded the minds of the unbelievers, that the illumination of the glorious good news about the Christ, might not shine through."(2 Cor 4:4)
The apostle John, in about the year 98 C.E., said: "We know we originate with God, but the whole world is lying in the [power of the] wicked one."(1 John 5:19) The only ones who are not under Satan's manipulative control, knowingly or unknowingly, are those who closely follow in Jesus footsteps.(1 Pet 2:21)
Today, however, Satan the Devil is more active than any time in human history. Since his being cast out of heaven in 1914 C.E., when Jesus took the reigns of God's kingdom (Dan 7:13, 14), he is now more busy than ever causing chaos and troubles. Revelation 12:7-9 says that "war broke out in heaven: Mi´cha·el and his angels battled with the dragon, and the dragon and its angels battled but it did not prevail, neither was a place found for them any longer in heaven. So down the great dragon was hurled, the original serpent, the one called Devil and Satan, who is misleading the entire inhabited earth; he was hurled down to the earth, and his angels were hurled down with him."
Because he no longer posed any threat to the angelic hosts in heaven following his ouster down to the vicinity of the earth, Revelation 12:12 says: "On this account be glad, you heavens and you who reside in them! Woe for the earth and for the sea, because the Devil has come down to you, having great anger, knowing he has a short period of time.” Satan now knows that his time period is "short", a very confined time allotment, compared to the time prior to his being cast out of heaven. He is indeed very angry for having been restrained in both space and time.
Throughout the earth, he is causing disruptions, terrorist activities, wicked acts of humans against humans, degraded and demoralized people roaming everywhere, with the only intent is to do deadly harm, just as the Nephilim (the wicked sons born to the rebel angels that materialized before the Noachian Flood, fathering hybrid offspring, Gen 6:4). These wicked and demented conditions are proof of Satan's rulership over the earth. Yet, his rulership has a limited time frame, for God had purposed that he be put into the "abyss", or state of inactivity for one thousand years following the battle of Armageddon.(Rev 16:16; 20:1-10) This allows for the earth to be transformed into a Paradise.(Luke 23:43)
Satan will always be a threat as long as he is alive and active. But, following his release from the sleep-like abyss (of one thousand years) at the end of Jesus thousand year reign and his subsequent attempt to once again rule the earth, he, along with his demon angels and those who have followed his rulership, will be permanently destroyed.(Rev 20:7-10) Satan, or anyone for that matter that proves to be rebellious (Prov 2:21, 22), will never exist again, to devastate the "abundance of peace" that God said would encapsulate the earth forever for "meek" ones, just as God purposed "from the beginning".(Matt 19:4; Ps 37:11, 29)