The keyword/phrase "proficiency of usage" relates to, and is part of, the classification(s) listed below, as used in the text or auxiliary documents of the QUFD website and in Father Jerome's scientific writings.
education
linguistics
reality
society
theology of reality
The GENERAL CONTEXT of such use is:
The term refers to the use of the English language in any form of communications. Proficiency of usage occurs with properly-learned "classical" American-English, resulting in excellent communications. Proficiency of usage is less so with "business" English, leading to misunderstandings and other negative implications, as Satan does so desire. See the listings for "Classical American-English" and "business...(et al)", and "clarity of understanding".
Also see Father Jerome's BLOG, for info about his latest Book,
"God, Lucifer and You! A ScienceBook of Quantum Physics and Reality, for 5 year old Kids and Adults!"