First, let us ask a preliminary question: What are demons? Demons are fallen angels, spiritual beings who joined in Satan’s rebellion against God. The NT speaks of the fallen angels in a couple of places:

[2 Peter 2:4 NKJV] 4 For if God did not spare the angels who sinned, but cast them down to hell and delivered them into chains of darkness, to be reserved for judgment.

[Jude 1:6 NKJV] 6 And the angels who did not keep their proper domain, but left their own abode, He has reserved in everlasting chains under darkness for the judgment of the great day.

In both of these passages, the biblical author makes references to “angels who sinned” or “angels who did not keep their proper domain.” These are the fallen angels, or demons.

As angels, demons are (as we said) spiritual beings. They are invisible, intelligent, powerful beings who, as the NT teaches, delight in tormenting people. In Revelation 9, they are depicted as an army of locusts sent to torment the wicked for five months. In that same chapter, they are also seen as a vast horde of horsemen 200 million strong as they go out to kill a third of mankind. They are malicious and evil and beyond redemption. Their fate is determined by God and they will be cast into the “everlasting fire prepared for the devil and his angels” (Matthew 25:41).

We also need to make sure we state that the devil and his angels are not “equal and opposite” forces to God and His angels. God is sovereign and in control of all things. He alone is eternal and the Creator of all things — including the angels. And the fall of Satan and his angels was according to the predetermined plan of Almighty God.

Now, having established that, why do we see such an increase in demonic activity during the earthly ministry of Jesus? We have to consider that the advent of Jesus Christ into this world is the culmination of God’s redemptive plans. Ever since Satan tempted Adam & Eve in the Garden of Eden, redemptive-history has inexorably been moving to this very moment. Recall the promise God made back in Genesis 3:15:

[Genesis 3:15 NKJV] 15 “And I will put enmity Between you and the woman, and between your seed and her Seed; He shall bruise your head, and you shall bruise His heel.”

This passage is commonly called the proto-evangel, or the first mention of the gospel in the Bible. This promise is fulfilled on the cross as Jesus deals the death-blow to sin, death, and Satan.

Consider all the ways in which Satan and his minions attempted to derail Jesus. Herod attempted to kill Jesus when He was a child, Satan tempted Jesus to short-cut His mission, Peter even told Jesus He would not go to the cross (and Jesus tells him “get behind me, Satan”), and right before the crucifixion, we see Jesus praying to God to take the cup from His hand (it’s not explicitly stated, but it’s not far-fetched to speculate that Satan was tempting Him again).

So the reason we see so much demon activity during Jesus’ earthly ministry is because Satan and his minions are doing everything they can to stop Jesus from accomplishing His divine mission. Recall all the times in the Gospels we see people trying to arrest or kill Jesus and Jesus manages to slip away. This is all part and parcel of Satan’s attempts to hinder Jesus. Satan even wanted to take Peter, but Jesus prayed for him (cf. Luke 22:31), so he settled for Judas (cf. Luke 22:3).

In answering the second part of the question (is demon possession possible today?), we need to consider what demon possession is. The word commonly used in the NT for “demon possession” is the word daimonizomai, which literally means “to be under the power of a demon.” We need to be careful in understanding this word. We don’t want to understand it to mean that the person who is demon-possessed is not responsible for what he/she does. We don’t want to adopt the Flip Wilson defense (“The devil made me do it”). When “Satan entered Judas,” it wasn’t as if Judas was minding his own business and all of a sudden Satan possessed him and he now wanted to betray Jesus. Judas was always going to betray him. A person cannot be demon-possessed who wasn’t already a sinner or hasn’t already given themselves over to sin.

So can there be demon-possession today? Short answer: Yes. Paul talks about unbelievers as those whom “the god of this age (Satan) has blinded, who do not believe” (2 Corinthians 4:4). Peter talks about Satan as a “roaring lion seeking whom he may devour.” In the last days, Satan (who has been bound for 1,000 years) will be loosed and he will “deceive the nations…to gather together to battle.” All of these passages speak of how demon-possession works today. Demon-possession is being blinded, being deceived, being devoured by Satan and his minions. But the good news is this is not something that can happen to believers! Believers are temples of the Holy Spirit, and greater is He who is in us than he who is in the world!