It is Scriptural. It is biblical truth. Saying "I will stick with the Bible" and then denying its truth is futile. It is a paradoxical statement that doesn't even make sense.
We do not have two natures.
Then why would Paul write of the war between the flesh and the Spirit -- using the two words 13 times each in Galatians 5?
It goes against the nature of a believer to sin.
It goes against the nature of God within him/her. It does not go against the nature of the flesh. That is where the deniers of the dual nature get it wrong. They do not understand that it is not the flesh that is put to death, but the corruption of the flesh inherited from Adam.
Sin is a choice born from a lack of faith and love ...
So every time you sin, and you and I both know we
both do, your lack faith and love? Really? You honestly believe that is the reason?
... but it is not our nature and that is why it is so painful once done. We are not battling a nature, but wrestling against the flesh just ike the Lord did while here on earth. He did not have two natures and neither do we.
You realize, of course, that the statements you make in that last quote argue
for the dual nature, not against, right?
The refusal to believe the existence of the dual nature is the result of a simplistic understanding of "flesh" and "nature."