v. 24 — This is the disciple which also beareth witness of these things, and wrote these things…

I think no wise man will doubt that the Lord would not have loved John if he had not been specially remarkable for virtue, and apt and perfectly equipped for every good work. For God can never be found to be inclined by any irrational leanings to those unworthy of His love, for such affections are more worthy of men. And He that was wholly proof against every assault and inroad of passion, and trod firmly in the path of every virtue, nay rather, was Virtue itself in all its forms, most assuredly would act in this, too, with judgment, and have His inclination free from all reproach----I mean, the inclination which led Him to deem him to whom this boon was due worthy of His love. After this admirable preface, then, and after having said that he was beloved, he modestly and with great humility says that he testified of these things; well and admirably inviting his hearers, as a necessary consequence, to assent to the things which he had written, and of which he had testified; for the preacher of truth cannot lie. Therefore, also, he says: We know that His witness is true. Dangerous, then, and awful is it assuredly, to lie at all; for man knoweth not how to bridle his tongue, and the Truth cannot love him that sinneth against truth.

CyrJn 12.24.1