Please read Luke 10:17-20 - What are you rejoicing in?
Seek the help of the Holy Spirit in understanding God's Word.
V17. The seventy-two return.
The seventy-two return. We are not told how long they have been away, but it probably wasn't too long given the number of them, the size of the region, and the fact that Jesus is on his way to Jerusalem. What we do know is that they all came back, filled with joy and excitement. Although Jesus had warned them about possible rejection, it seems like they were well received wherever they went, or if they were not, it hadn't affected them adversely. What has really excited them is the way they have been able to heal people who were demon-possessed. They are giddy with the news that demons were submitting to them when they proclaimed the name of Jesus.
V18. Jesus tells them the background.
Jesus doesn't get carried away with what these men have been able to do. He doesn't join in their excited chattering but explains why they have been able to do what they have done. There are three lines of thought on Jesus' response. Some think that the genesis, the root of what they have just been experiencing, goes back a long way. Back before time in eternity, a place where time does not exist. Back to the day when Satan was expelled from heaven because he rejected the rule of God because of his pride. Others say that it refers to what happened in the wilderness when Jesus met and defeated Satan by not succumbing to his temptations. And some say they just don't know and want to leave it at that. I favour the first explanation, i.e., that it took place in eternity in heaven.
Jesus describes Satan's fall which he witnessed, not with his physical eyes, but because he was in pre-incarnate form in heaven when it happened. He says it was like lightning, which could be understood in terms of the speed and shocking effect of the event. Beyond that, we are not told anything more, so we have to leave it at that. The point, though, is that the work of the seventy-two is part of something that has been ongoing since before the beginning of time and needs to be put into that context. Therefore, their joy should look for somewhere else to rest on, that is, other than merely the victories they have had over the demonic.
V19. Christ gives authority.
Jesus goes on to speak of the authority that he has given them. It is the authority to tread on, destroy serpents and scorpions. Is Jesus referring to a literal ability to stand on a snake or a scorpion and kill it, or is he talking about something else? I believe that he is talking about something else. He is telling these men that they have power in his name to destroy the cohorts, the allies of Satan. Yes, it is true that the apostle Paul did survive a viper bite on the island of Malta, Acts 28:5, but that was a unique case of God preserving Paul. This is something entirely different.
Serpents and scorpions are symbolic of those who participate with Satan in his spiritual warfare against Christ, and the Kingdom of God. A spiritual warfare that is, and will be, unsuccessful for Satan and those allied with him. We have the promise of God to Satan in Genesis 3:15, that the seed of the woman, Christ, will crush his head as Satan, destroy him as he strikes Christ's heel – the cross. David speaks of the destruction of Satan's spiritual allies, the adder, the lion, and the serpents through their being trodden upon in Psalm 91:13. Christ has now given this authority to these men. And note, it is not just authority over Satan's cohorts; it is an authority over Satan himself – "over all the power of the enemy".
The statement, "and nothing shall hurt you", means that neither Satan nor any of those allied with him can inflict with persecution and death at will. Satan does not have the ability. He does not have the power to act when and how he pleases. He is a real spiritual being, who does prowl around the world, like a roaring lion, seeking those he may devour, 1 Peter 5:8, but he is only allowed to act when God permits him.
Like all angels, Satan is a created being who depends on God for his existence. Even though he lives that existence in relentless, vengeful rebellion against God, he does so in perpetual subordination to God, Job 1:6. He has limited knowledge and power, and can only be in one place at a time; I Kings 8:39, Isaiah 46:9-10, Daniel 2:27,28, Job 1:12,16,19. Satan cannot tempt without God's permission, Job 1:12. He was only able to tempt Jesus in the wilderness because Jesus had been led into the wilderness to engage with Satan by the Holy Spirit, Matthew 4:1. He can cause no physical harm or kill without God's permission, Job 2:2-6, even though the Bible says that he has the power of death, Hebrews 2:14. Satan can neither mention a believer's name nor force a believer to do anything without God's permission, Job 2:3, Acts 26:18.
V20. Rejoice that your names are written in heaven.
Jesus is telling these men that the reason they have experienced victory over Satan is because of his power and authority over Satan. What they should be getting excited about is the fruit arising from the defeat and not the defeat itself. The fruit being their salvation and the salvation of others. Getting caught up in the ability to do things in Jesus' name is dangerous. At the end of the Sermon on the Mount, Jesus taught just how dangerous that could be. "Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. On that day many will say to me, 'Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?' And then will I declare to them, 'I never knew you; depart from me, you workers of lawlessness.' Matthew 7:21-23. Just because someone can do amazing things, including casting out of demons, it means nothing come the Day of Judgement. What matters on that day is whether one's name is written in the "Lamb’s book of life", Revelation 21:27. For Jesus, that is the critical point and the only reason for rejoicing. And what a wonderful, glorious reason that is. To know that your name is written in heaven, declared justified in the sight of God, accepted by adoption as one of his children, sealed into an eternal inheritance guaranteed by the promised Holy Spirit, to the praise of God's glory, is truly something amazing, Ephesians 1:3-14.
You want to rejoice in the defeat of Sin and Satan's power – then rejoice in the new life you have in Jesus Christ. You want to get excited – get excited about living daily for the Lord. Having the privilege to do that, through and by the love, mercy, and grace of God, is the most unbelievable reality on the earth.