Anything added to the work of Christ on the cross means that what Christ did wasn’t good enough, that we have to add more to it to make it adequate.
That is spitting in God’s face, treating the death of Christ with contempt as useless.
No, actually what's spitting in God's face is pretending that 100% of His Revealed Word is contained in the Bible and that it took a French shyster 1500 years after Christ's death to tell the world which parts were relevant and which parts could be ignored.