But as for those that have vowed a chastity, they must make use of other means to prevent this burning, particularly prayer and fasting. But what
a wretched casemust that of
the adversaries of the celibacy of the clergybe, when to maintain it they nave in so many places wilfully corrupted the scripture ? and what a melancholy case It must be, that so many thousands of well-meaning souls should be wretchedly deluded with the pretence of God's pure word, when instead of this, they have nothing put in their hands but corrupted translations, which present them with a mortal poison, instead of the food of life ?
How do you determine/deduce the syntax of the subordinate clause with the bolded? Please explain and show all steps and thought processes. I first tried to ignore 'nave in so many places':
...when to maintain it [=
a wretched case]
they [ie =
the adversaries of the celibacy of the clergy]
wilfully corrupted the scripture ?
Yet afterwards, I still can't resolve where nave in so many places fits?
Footnote: I lit on this work only while reading definition c. for 'to vow' on OED.