Very simple to answer.
1, your use of 'flesh' is mistaken. There is nothing evil about the body, sex, food, history. 'Flesh' in the NT means the depraved nature of man, about which he is often in denial. Through that basis, 'flesh' can sometimes also mean 'lineage' or 'descendancy'. And of course, it means lust, which is the reckless use of a good desire. If this distinction is not kept, even marriage is evil.
2, In case #1 is too general for you, let's see a specific example in historical work in action. Luke 19:46. The term in NIV is 'robbers.' But there is a historical problem here. The Greek is 'leistes' and 'leistes' is never a simple robber. It is always a politically-motivated robber: an insurgent, an insurrectionist, a brigand. There are several other terms for the simple robber. So why did Luke choose this?
In Luke, especially, there is attention to what the zealots are doing in both his gospel and in Acts, and the introduction to each is for a person who represented Paul (an attorney) probably about this question of association with zealots. In Acts 21 he is misidentified as one. In Lk 19, Jesus had just said (vs41+ right before 'cleansing') that the temple would be demolished shortly because ideally the Jewish person who heard Christ was supposed to be a missionary for the Gospel. The opposite of that, of course, is a zealot who joins the rebellion (predicted in Dan 8:13, and mentioned again in 9) to 'liberate' Judea.
So now we see what Jesus is complaining about at the temple: it is raising money for insurrectionists! We then see something happen that is pretty shocking, yet approved by the crowd that worships at the temple: they want the release of a KNOWN terrorist over Christ! Now, in the text, immediately after this we find Jesus warning the generation AGAIN about what would happen. By the time the children are adults, they will be doing worse than what was just forced on him. The upshot: the place will be overrun by insurrectionists and self-destruct, which is what happened to Israel in the 6th decade, 40 years later.
Luke definitely wrote this to clarify that Paul was not part of the zealot insurrection movement. It was not the only purpose, but it was covered clearly.
It is unfortunate that people think the Bible has no historical value or just don't seem to know what historical value is.
