Scripture is an all or none deal. Either you embrace all of it as authoritative and applicable or you don’t embrace any of it in that capacity. That sounds overstated and perhaps at some level it is. Obviously there are hermeneutical principles that must be applied. Yet some people approach the text in a selective way. Revisionists like to pick and choose which parts of the Bible are authoritative for today. But if you claim certain parts of Scripture are irrelevant, who’s to say the parts that remain are relevant?
If the teachings of Scripture around issues like marriage, sexuality, and the sanctity of life don’t apply, then how can you be sure issues like salvation, the forgiveness of sins, bodily resurrection and eternal life do apply? Once you diminish the authority of one part of Scripture you’ve diminished the authority of all of it. Do you really want to bank your eternal destiny on revelation that, in your estimation, goes out of date with the passage of time?