17The seventy returned with joy, saying, "Lord, in your name even the demons submit to us!" 18He said to them, "I watched Satan fall from heaven like a flash of lightning. 19See, I have given you authority to tread on snakes and scorpions, and over all the power of the enemy; and nothing will hurt you. 20Nevertheless, do not rejoice at this, that the spirits submit to you, but rejoice that your names are written in heaven."
The context for this very short passage:
Jesus has given instructions for proclaiming the reign of heaven, Kingdom of God on earth. He wisely advises everyone to travel in pairs (just as everyone now has been insisting kids always do on their way to and from school, or going anywhere); Jesus tells them to announce the presence of the Realm of Shalom to all they encounter. They need to accept the hospitality and act as guests of households they visit. Eat whatever people give you! "You are what you eat" – "we are what we eat" – we are our hosts. They and we are one.
Eating "whatever" would have been a major problem for people with religious dietary laws; in Luke Volume 2, his Acts of the Apostles, we read a fame account of God declaring all food that's a gift of creation good:
9About noon the following day as they were on their journey and approaching the city, Peter went up on the roof to pray. 10He became hungry and wanted something to eat, and while the meal was being prepared, he fell into a trance. 11He saw heaven opened and something like a large sheet being let down to earth by its four corners. 12It contained all kinds of four-footed animals, as well as reptiles and birds. 13Then a voice told him, "Get up, Peter. Kill and eat."
14"Surely not, Lord!" Peter replied. "I have never eaten anything impure or unclean."
15The voice spoke to him a second time, "Do not call anything impure that God has made clean."
16This happened three times, and immediately the sheet was taken back to heaven.
Luke 10:17 – the number 70 combines 7 – the number of perfection and 10 – the number of completion in Hebrew numerology
Luke 10:18 "I watched Satan fall from heaven like a flash of lightning." Jesus declares Satan, the powers of evil, the devil, oppressive imperial structures, ecological degradation, (insert long list here),everything that hinders life no longer has power, authority, staying power, or sovereignty. Jesus holds all power and authority with no checks or balances.
Although we need to live – and work – without fear as God's hands, feet, voices, minds, imaginations, we can trust God already has been at work in the world before God leads us to a particular situation—God has been to our future! That's sometimes called the previousness of God.