D'accord! But seriously, the context is in the churches of God and in Christian service.

In this context, if all (Christians) are to speak as if speaking the very words of God, then what is the distinction enjoyed by the one who would be the substitute for Christ on earth?

IMHO either there are many fewer or many more legitimate priests than what we find in the Roman Church. In my New Testament, mentions of 'priests' are one of three categories: 1. Unfavorable; 2. Singular as in Christ our great High Priest; or 3. Referring to the universal priesthood of present and future believers.