Douglas Harper's Etymology Dictionary
unscriptural
1650s, from un- (1) "not" + scriptural (adj.).
Wiktionary
unscriptural
a. Not scriptural.
Usage examples of "unscriptural".
But it's an impious, unscriptural opinion to say a woman's a blessing to a man now.
It was this employment of the phraseology of Scripture to convey doctrines utterly unscriptural that rendered their teaching such a snare to the unwary.