My guess is that the only Christians that have this world view of not hearing about demons being cast out of people today like they were in the bible do not fellowship with believers who believe the scriptures that believers will cast out demons and therefore cast out demons.
I suggest attending and Assemblies of God Church for a year and you will discover that all of the signs and spiritual gifts that occurred in the New Testament 1st Century church, healing, speaking in tongues, casting out devils do continue to occur among those that believe these scriptures.
When you fellowship with those who do not believe they happen today then of course they will not attempt to cast out a demon or even recognize one when it shows up. They will say that person is mental and leave them in that condition.
Demons are not mortal, the same demons that were teaching false doctrines in the first century are still around also. That is why Jesus called it the doctrine of Balaam and Jezebel, and the leaven of the Pharisees. We should be able to recognize it when we hear it even if it is disguised under new names, the same demons are behind it.
The reason you don't see it is because the people you are around or who are in your world of influence do not believe it. I have seen it for years in the Assemblies of God.
A favorite argument of those who do not believe in healing for today say that if it were real people would be going to the hospitals. They do. People who believe in healing in the name of Jesus go to hospitals all over this world and people in hospitals are healed every month as a result. Documented miracles happen and Doctors give glory to God. But you won't hear about it on the news because people don't believe. However, go visit the churches who have hospital visitation ministries and your world view will change from "why don't they go to hospitals" to "oh.. my bad.. they do"
it’s strange that believers don’t believe in spiritual things because the entire Bible is about spiritual things . In fact God is a spirit himself . Our struggle is entirely spiritual in this world
“Put on the whole armour of God, that ye may be able to stand against
the wiles of the devil.
For we wrestle not against flesh and blood, but
against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
Wherefore take unto you the whole
armour of God, that ye may be able to withstand in the evil day, and having done all, to stand.
Stand therefore, having your loins girt about
with truth, and having on the breastplate of
righteousness;
And your feet shod with the
preparation of the gospel of peace;
Above all, taking the
shield of faith, wherewith ye shall be able to
quench all the fiery darts of the wicked.
And take the helmet of salvation, and
the sword of the Spirit, which is the word of God:”
Ephesians 6:11-17 KJV
temptation is a spiritual thing that appeals to the flesh , we overcome it by the spirit , the word of God and our faith that produces.
the kingdom of God is a spiritual belief , it’s where we begin to recognize what’s actually happening in this world the spirit and flesh connection .
spirit is intended to
Live in flesh those two aspects create a living existing being heaven is spiritual earth is natural , mans flesh cane from earth , the spirit from heaven .
all through scripture these two aspects intersect again and again The heavens and the earth were torn apart the spirit and flesh by sin through man
And the reconciliation also of spirit and flesh , heaven and earth comes through the new man Christ Jesus and his truth