For me it is a question of why we use, or should use, extra-biblical terms when we can use the language of scripture. Depending on what
@JIM means by "
biblical" (such appeals often create ambiguity), he may be correct because the phrase is not found in scripture but, on the other hand,
@Arial is correct because the nature of humanity is individually and collectively sinful. The fact the phrase isn't found in scripture does not mean it can't be used any more than the fact the concept can be inferred does not mean the phrase should be used. Since the phrase the scriptures use is "
flesh" (The New Testament Greek is "
sarx"), it is accurate to say, "
sinful flesh (Gk.: flesh of sin)." Dynamic translations like the NLT use the phrase "
sinful nature" when the formal translations say "
flesh." (see
Romans 8:12,
Galatians 5:17, or
Colossians 2:13, for examples). It's worth noting the NIV used to use the phrase "
sinful nature" but now uses "
flesh" (my 1984 and 2005 copies of the NIV have "
sinful nature" instead of "
flesh" in all three of those verses). A generation raised on the NIV was trained to use "
sinful nature."
It's one of the reasons I prefer the NAS and the ESV.
@JIM, the validity of "
sinful flesh" was
disputed earlier but verses like Psalm 38:3 and Romans 8:3 makes it clear flesh is sinful, both phrases and the concepts are valid, and it's firmly rooted in scripture (even if I prefer not to use the word "
nature"). When the Bible speaks of something being "fleshly," it is always about something sinful. God made the flesh good (Gen. 1:31). Sin changes the flesh. The flesh is not as God created it.
That is why GotQuestions bothered to describe sin nature.
None of it, however, has anything to do with
evolution.