{Sinneth not} (ouch hamartanei). Linear present (linear
men(936e), keeps on abiding) active indicative of hamartan(935c),
"does not keep on sinning." For men(935c) (abide) see  2:6  Joh
15:4-10 . {Whosoever sinneth} (ho hamartan(936e)). Present (linear)
active articular participle like men(936e) above, "the one who
keeps on sinning" (lives a life of sin, not mere occasional acts
of sin as hamart(8873)as, aorist active participle, would mean).
{Hath not seen him} (ouch he(9372)aken auton). Perfect active
indicative of hora(935c). The habit of sin is proof that one has not
the vision or the knowledge (egn(936b)en, perfect active also) of
Christ. He means, of course, spiritual vision and spiritual
knowledge, not the literal sense of hora(935c) in  Joh 1:18  20:29 .