One thing that my advisor really emphasized to me was that I needed to learn classical Greek and use classical Greek lexicons when reading the New Testament, because often the NT-only material can be misleading. At the same time, obviously language evolves over time, so I can never be sure whether I’m picking up on something real. Case in point: the use of “τὰ φαῦλα” in John. It’s translated as something like “evil” most times I’ve seen it so far, yet the classical lexicon indicates that it means something like “trivial.” As an example, take John 3:20:
πᾶς γὰρ ὁ φαῦλα πράσσων μισεῖ τὸ φῶς καὶ οὐκ ἔρχεται πρὸς τὸ φῶς, ἵνα μὴ ἐλεγχθῇ τὰ ἔργα αὐτοῦ·
For all who do evil hate the light and do not come to the light, so that their deeds may not be exposed. (NRSV)
The next verse contrasts doing φαῦλα with doing τὴν ἀλήθειαν (the truth), and it seems at least interesting to think of a contrast “true/trivial” vs. “true/evil” — then the doers of triviality wouldn’t be hiding their deeds out of some motiveless malignancy or even a fear of God’s punishment, but because they’re embarrassed that they’ve essentially wasted their lives on things that don’t matter.
And yet I could be entirely making this up.