Skeptics like to claim that there are so many differences between copies of the New Testament manuscripts that you can't trust the text. Christians counter that the many variants actually make it easier to ferret out the most likely original wording, and in any event, no major point of docrine hangs on a textual variance.
But then we run into Hebrews 6, which warns that a person who has been saved and then falls away cannot be bought back to repentence because they are re-crucifying Christ and holding Him up to ridicule.
Because. That's really scary stuff - it seems to say that if you once make shipwreck of your faith, you're permanently hosed. That's pretty major.
But wait - the NIV footnote says that some manuscripts say while, not because.
While leaves some wiggle room. It allows for a fallen-away believer to come back if they stop, um, falling away. But that's not just wiggle room - it seems like a very different doctrinal point entirely. Can believers who fall awy be reunited, or not? That seems like a binary question. It's either-or, isn;t it? And if because - the harsher reading - is correct, what does that say about God's grace? (Isn't there a passage somewhere about an unforgivable sin?) And what does it say about our supposedly sure hope?
We are very fortunate that we have more than one English translation. Let's look at some others.
The NASB uses since: they can't repent since they scorn Christ. That also give the sense of, if they'd only stop, they could be brought back. The KJV says, seeing that. That also implies an action that is currently happening.
Not an action in the past that has irrevocably set the course of the future.