en_tn/3jn/01/12.md

Demetrius is borne witness to by all

This can be stated in active form. AT: "All who know Demetrius bear witness of him" or "Every believer who knows Demetrius speaks well of him" (See: rc://en/ta/man/translate/figs-activepassive)

Demetrius

This is probably a man whom John wants Gaius and the congregation to welcome when he comes to visit. (See: rc://en/ta/man/translate/translate-names)

by the truth itself

"the truth itself speaks well of him." Here "truth" is described as a person speaking. AT: "everyone who knows the truth knows he is a good person" (See: rc://en/ta/man/translate/figs-personification and rc://en/ta/man/translate/figs-explicit and rc://en/ta/man/translate/figs-rpronouns)

We also bear witness

What John is confirming is implied and can be made specific here. AT: "We also speak well of Demetrius" (See: rc://en/ta/man/translate/figs-ellipsis)