They asked Jesus is literally “The Jews answered and said to him.” Since a new section begins here, Good News Translation makes clear that the pronoun “him” refers to Jesus, and on stylistic grounds the Semitic redundancy “answered and said” is reduced to asked.
The question raised by Jesus’ antagonists indicated that they assume the answer is “Yes.” It is a rhetorical question and in some languages may be made a strong declarative statement, for example, “We were certainly right when we said that you are a Samaritan and have a demon in you.”
It is not known precisely what is meant by the accusation that Jesus was a Samaritan. Some commentators believe that it indicates that his accusers thought Jesus was heretical, while others believe it is the equivalent to the accusation that he was demon-possessed. The second of these two judgements is probably the true one, especially in light of the fact that only the charge of being demon-possessed is replied to by Jesus (verse 49).
You … have a demon in you is literally “you have a demon” (so Revised Standard Version). Jerusalem Bible translates the accusation “possessed by a devil” (Die Bibel im heutigen Deutsch “possessed by an evil spirit”) and Jesus’ answer “I am not possessed.” Moffatt renders the charge “you are mad” (see also Phillips). New American Bible translates the whole accusation “you are a Samaritan, and possessed besides.” To translate “you are mad” fails to convey the proper cultural impact, since in biblical times the Jews believed that madness and insanity were brought on by demon possession. Jerusalem Bible makes clear that demon possession was the charge brought against Jesus, and this information is implicit in the way Jesus’ answer to the accusation is structured. It is possible that a reader of New English Bible might fail to understand what is indicated by the accusation “you are possessed.” It is important that the aspect of demon possession be made clear for the reader, since this belief was an essential part of the cultural situation of Jesus’ day.
As already noted, different languages refer to demon possession in different ways, for example, “he is commanded by a demon,” “a demon controls him,” “a demon marches inside of him,” or “a demon occupies his heart.”
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 .