I believe in extra-biblical truths.
And so do you.
For example, I believe that water is made of hydrogen and oxygen. That's extra-biblical. I believe that electric cars transfer pollution to electricity-generating power plants. That's extra-biblical. I believe the quartz movement is more accurate than the traditional Swiss movement. That's extra-biblical. I believe coffee should be drunk without milk or sugar. That's extra-biblical. (And an opinion, what's more.)
Even the Amish, who've decided to freeze time in the horse-and-buggy era, have electric turn signals on their buggies.
We're all extra-biblical. We're all hypocrites. "Let God be true and every man a liar." That's biblical.
My point? Relax. Don't be so anxious to live only-biblically. Don't be so anxious to point out what's biblical and what's not. Chances are, you don't really know.