A devout Christian couple who failed to get medical treatment for their sick child have been convicted and discharged after what a judge described as "an error of judgement".

Herman Jongkind, 38, and Trijntje Jongkind, 34, of Ruatangata had pleaded guilty in the Whangarei District Court to one charge of failing to provide the necessaries of life to their 17-month-old son Jesse over a four-week period last year.

Judge Michael Lance QC sentenced them yesterday.

In court for the sentencing were their eight children including Jesse who appears to have fully recovered.

During a part-heard trial last month, the Jongkinds admitted diagnosing Jesse with life threatening meningococcal meningitis using a text book.

They did not take him to a doctor for almost four weeks.

Instead they asked members of their Pentecostal church to pray for the boy, believing that God would "heal him or take him".

Crown prosecutor Kim Thomas yesterday referred to evidence from a paediatrician who treated Jesse that the boy faced a 95 percent chance of death if untreated.

Conventional treatment in the form of antibiotics reduced that risk to less than five percent, Mr Thomas said.

The Jongkinds changed their plea earlier this week. Defence counsel Arthur Fairley said the couple's ninth child was due in January and did not want the ongoing stress of awaiting trial.

He argued the pair should be convicted and discharged, as no further penalty was needed. The couple accepted they had a responsibility to take their children to the doctor if sick.

Judge Lance said he was prepared to trust that the Jongkinds would in future seek medical advice when necessary.

"I want your children to understand that was all it was - an error of judgement, a simple mistake which was, it turned out, quite serious but understandable.

He did not want the sentence to be seen as "soft".

"People who do not get medical attention for ill children are committing a crime, and a serious one which carries quite serious penalties."

Judge Lance urged supporters who filled the public gallery to "keep an eye" on the Jongkinds and to not be frightened to report any concerns they had about the care of the children: "You'll be doing them a favour."