Good News Translation places this verse in parenthesis, indicating that it is an explanatory statement interrupting the flow of the narrative. So also Moffatt and New American Bible. New American Bible, however, misses the force of believed in, “not even his brothers had much confidence in him.” The force of the verb here is definitely that of “to believe in” or “to place one’s faith in,” not a more general meaning as New American Bible suggests. New English Bible (“For even his brothers had no faith in him”) likewise implies the more general idea of confidence, rather than faith.

It may be difficult to render the idea of Not even his brothers. It may even be necessary to say “his brothers didn’t believe in him; and one would certainly have expected that they would” or “one wouldn’t have thought so, but his brothers didn’t believe in him.” The emphasis here is upon a statement which though true, is contrary to expectation.

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .