It would seem that there was a spike in demonic activity on earth at the same time that the Son of God was on earth. We don't know the reason, but it could be that since Satan failed to tempt Christ, he tried to show his power through an increase in demon-possession and oppression.
We do not see this kind of activity in the OT, although there is no doubt that demons have been plaguing people ever since the Flood. Paul identified all the pagan false gods as demons, and occultism and shamanism have existed in every part of the world, particularly in the primitive regions, and they continue to be powerful in Haiti, Africa, etc.
Because of the secular humanism which pervades Western societies something which gets overlooked today is the connection between psychiatric problems and demonic activity. Mental health practitioners are trained to ignore the spiritual altogether, and use medications to deal with spiritual issues (with zero results). But schizophrenia and similar disorders seem to be demonic, and many criminals who committed very evil deeds claimed that they heard voices telling them to do whatever they did.
Over the last few decades, there can be no doubt that Islamist fundamentalism and jihad are controlled by Satan and his demons, since the atrocities committed by the jihadists can only come from totally evil hearts possessed by demons. Ayatollah Khomeini was probably possessed by Satan, as was evident in his face, his demeanor, and his proclamations. But the ignorant and foolish Western politicians could not grasp what he was saying, and hundreds of thousands of innocent lives have been lost because of this stupidity. The Koran was a very clever production of the devil masquerading as Jibril/Jibreel (the angel Gabriel). Some claim that Islam is an invention of the Catholic church (which may or may not be true), but there is no doubt that Mohammad was familiar with Roman Catholicism, since the Koran refers to it obliquely.
However, it is interesting to note that it is the Catholic Church which leads in *exorcisms*, even while they do not hold to Bible Christianity. In any event, this is another indicator that Satan's influence on earth will grow until the Antichrist is revealed.