discernment: the trained ability to tell things apart and judge their true character
At its core this word names an act of sorting: taking things that look alike and telling which is which. In the New Testament that sorting is always evaluative and skilled, not a passive hunch. It is the settled capacity of a mature person to separate good from evil, or the God-given ability in a gathering to tell a genuine spiritual influence from a false or merely human one.
The two New Testament uses in this sense share that core but aim it at different objects. In Hebrews the object is moral: a grown believer, through long practice, can distinguish what is good from what is harmful the way a trained palate tells foods apart. In First Corinthians the object is the source and worth of what claims to be Spirit-prompted speech in the assembly. Scholars still debate exactly what that gift weighs (see the note on that verse), but the underlying idea is the same evaluative act.
The common English word "discern" can suggest a vague intuition. The Greek is more active and disciplined than that: a worked-at skill of judging, closer to practical wisdom than to a spiritual feeling.
Nuances
What the gift called "distinguishing of spirits" in 1 Corinthians 12:10 actually evaluates.
- majorityThe origin of an utterance: whether a pneumatic utterance comes from God, from a demonic spirit, or from a merely human source. The closest conceptual parallel is 1 John 4:1, and the background is the Qumran Two Spirits treatise.; Gordon D. Fee, The First Epistle to the Corinthians (NICNT, rev. 2014), 596-97; Hans Conzelmann, 1 Corinthians (Hermeneia, 1975), 209-10; Christopher Forbes, Prophecy and Inspired Speech in Early Christianity (WUNT 2/75, 1995), 218-29
- minorityThe content of prophetic utterances, weighed for truth; the "spirits" are the prophets' inspired utterances themselves, closely tied to the cognate verb in 1 Corinthians 14:29 and to 1 Thessalonians 5:19-21.; Wayne A. Grudem, The Gift of Prophecy in 1 Corinthians (1982); D. A. Carson, Showing the Spirit (1987), 93-100
- minorityThe interpretation of symbolic Spirit-revelations, a decoding gift standing to prophecy as interpretation of tongues stands to tongues, on the analogy of dream-interpretation in Jewish tradition. Largely rejected in English-language scholarship after Grudem's critique.; Gerhard Dautzenberg, Urchristliche Prophetie (BWANT 104, 1975), 122-48