Demons speak through people. Jesus always spoke with them. The Spirit of Antichrist is very active today in Oneness, Jewish, and antitrinitarian groups. How many "Christian" artists have abandoned the faith after singing one song after another laced with false doctrine?
Well, from what I understand, the devil, or a demon since there is only one devil, can enter a person as per things Jesus said. Or even Peter to Ananias for that matter. However, unless there is a trauma of some kind to a defenseless person, it usually requires the co-operation of the person in order for a demon to operate through people.
Also, Jesus actually told the demons to shut up. If you look up the words Jesus actually used, the translation should be 'shut up' At least that is what I read and telling demons to shut up in Jesus name is a great idea. Don't you think?
That way, we can be sure when we
are hearing from God who does still speak today by the way. First of all through His word, but also through His Holy Spirit who is our Teacher among other things. So, Jesus did not actually have a conversation with demons and it is my opinion that folks who do so today should be prepared to be lied to.
Jesus did ask the man filled with a legion of demons what their name was, but that is an exception I believe and let's remember, He is God after all and they had to answer Him, in fact, begging Him not to send them into some place without a body for a residence.
Jesus did have a bit of a conversation with the devil but the devil is not a demon and does not personally reside in people even though sometimes devil and demon are used interchangeably but that is not a right understanding.