Nicodemus,
You are contradicting yourself. You are not letting the Bible speak for itself. Yes, there are functions and offices within the church, and we could use it to just clarify who is doing what and who we are referring to as necessary, not as a title but as a clarification as necessary.
The early Christians in Acts followed the teachings of our Lord Jesus Christ regarding this topic. Will you?
BTW, Luke did use titles, ... to refer to earthly kings of this world:
Acts 25:13 (NKJV) And after some days
King Agrippa and Bernice came to Caesarea to greet Festus.
Also, Paul did use it:
Acts 26:1-2 (NKJV) 1 Then Agrippa said to Paul, "You are permitted to speak for yourself."
So Paul stretched out his hand and answered for himself: 2 "I think myself happy,
King Agrippa, because today I shall answer for myself before you concerning all the things of which I am accused by the Jews,
Use it for the world personalities if you will, but it is not appropriate for within the church as I showed you with Biblical Evidences. Show respect with action instead: with your submission, with your tongue.