The Book of 3rd John
"Demetrius has received a good testimony from everyone"

Bible Study and Commentary
James Deering,

conjunctions & prepositions underlined, words not in original text in italics)  (alternate text in purple)

3 John :12
Demetrius has received a good testimony
    from everyone, and
    from the truth itself; and
we also bear witness, and
you know that our witness is true.

Most writers agree that Demetrius is the man whom John used to carry this letter to Gaius. Demetrius comes highly recommended "from everyone." Johnís own commendation is that he is a man "from the truth itself." What a remarkable statement. Demetrius is apparently a powerhouse of "church correction." He is able with the Word of God, anc comes with the full confidence of not only John but also all of Johnís fellowship. John tops it off with (incase Gaius hasnít got the message yet) "you KNOW that our witness is TRUE." Demetrius is probably the reason why John says "if I come." John expect that Demetrius and his ministry will take care of the problem and possibly remove Dotrephes before his arrival.

Diotrephes -
the example to be Avoided
Demetrius -
the example to be Followed