An excerp from "The Devil's Digs":
They came from every direction to join the tight, close formation. Flying wingtip to wingtip. Had they been of the natural world, their presence would have blocked out the light of the sun as they passed between it and the valley below. But the darkness created by these vultures of the spirit world could be seen only with spiritual eyes.
“Snake-Eyes, when is the master going to give us physical bodies, like he promised?” a smaller demon called Slug asked the ghoul to his right.
“Shut up you fool, lest the master hear you and give you what you want. Don’t you know how cumbersome a physical body is? You can’t do this with a physical body.” He dove downward, out of formation and out of sight before the sound from his words had reached the ears of the foolish one. In a nanosecond he reappeared, coming from overheard.
Slug ducked his head.“Impressive, but, how can you frighten humans when they can’t even see you?”
“Our assignment isn’t to frighten them, you idiot. They do a good enough job of that to themselves with their wars and weapons of mass destruction. We’re to infiltrate their lives and destroy them from within. It’s a time-consuming process.
"If they’re already Christians, the best we can hope for is to get them to put their God on the back burner . . . not always an easy task. But we can consider our work a partial success if we sidetrack them to the point they can do no service for their King.
“If they’re not Christians, the master expects us to harden their hearts and bring them into submission to him. Severe punishment is meted out to anyone who fails to convert a likely candidate.”
Do Demons carry on conversations? That I don't know. That's part of the "fiction" in "honest Christian fiction."
Do they even exist? You bet. And they exist for the sole purpose of taking a Christian's eyes off of the Lord, and keeping unbelievers from ever meeting the Lord.
Why do they bother with good people who are already out of Satan's eternal reach? In an attempt to bring dishonor to God. You've read these headlines (or similar ones): "Pastor Involved in Love Triangle." Those five words have the power to discourage an unsaved person from pursuing a relationship with Jesus. Thereby condemning him to an etermity with the evil one.
Why do they care? They're taking orders from their master: Satan.
You say you believe in angels, but not in demons? Then my final question to you is this:
When Lucifer (Satan) was cast out of heaven and his "followers" (errant angels) chose to go with him, what do YOU think became of his followers?