This is a powerful passage which believers must claim! The Greek for the word "heaven", "oo-ran-os", implies not only heaven, but also eternity. The enemy was removed from the eternal places, and his power is only temporary in this world. Our power does not come from this temporary world, but from eternity, from the eternal throne of God.
If our focus is on eternal things, and we claim our authority from heaven, we can exercise power over the enemy. His attacks are temporary, and refer to our short life on earth, because his place in God's eternal realm was abolished and he was cast down. Drawing on the authority and eternal power of God, through Yeshua (Jesus) we can really tread on serpents and scorpions, overcoming the enemy's power. Whatever Satan sends our way is temporary and must submit to the authority we walk in when filled with the Holy Spirit.
Satan's removal from heaven is good news for us. He has lost his place in the eternal realm. This makes the trials and tribulations of our life on earth much less significant. They are "light and momentary" compared with the eternal glory which awaits us...a fleeting moment, for the enemy has been cast out of eternity and his destiny is the lake of fire! (George, Baht Rivka, Elianna & Obadiah)