Matthew 10:1 And when He had called His twelve disciples to Him, He gave them power over unclean spirits, to cast them out, and to heal all kinds of sickness and all kinds of disease.
Jesus could not say his disciples must go out and cast out demons if they don’t exist. You can’t say you follow a person if you don’t believe in his works. The Bible that we all use, says God does nothing without revealing to His prophets. Amos 3:7 Surely the Lord GOD does nothing, Unless He reveals His secret to His servants the prophets.
Most well-off countries denies prophets. What does this implies to the churches that exist in these countries? If deliverance and prophetic gifts are denied there are high chances you fellowship with devil worshippers everyday and they are sitting comfortably because they are not in danger.