{Is not judged} (ou krinetai). Present passive indicative.
Trust in Christ prevents condemnation, for he takes our place and
pays the penalty for sin for all who put their case in his hands
( Ro 8:32f. ). The believer in Christ as Saviour does not come
into judgment ( Joh 5:24 ). {Hath been judged already} ((8864)(880a)kekritai). Perfect passive indicative of krin(935c). Judgment has
already been passed on the one who refuses to believe in Christ
as the Saviour sent by the Father, the man who is not willing to
come to Christ for life ( 5:40 ). {Because he hath not believed}
(hoti m(8820)pepisteuken). Perfect active indicative of pisteu(935c),
has taken a permanent attitude of refusal. Here hoti m(885c) states
the reason subjectively as the judgment of the Judge in any such
case (ho m(8820)pisteu(936e) already mentioned) while in  1Jo 5:10 
hoti ou pepisteuken gives the reason objectively (ou instead
of m(885c)) conceived as an actual case and no longer hypothetical.
See  1:12  for eis to onoma with pisteu(935c) (believing on the
name) and  1:14  for monogenous (only begotten) and also
 3:16 .