This is now usually understood to mean a high faculty, enjoyed by certain persons in the apostolic age, of diving into the heart and discerning the secret dispositions of men. It appears to have been one of the gifts peculiar to that age, and was especially necessary at a time when the standards of doctrine were not well established or generally understood, and when many deceivers were abroad (). This faculty seems to have been exercised chiefly upon those who came forward as teachers of others, and with whose real character and designs it was important that the infant churches should be acquainted.

Bibliography Information
Kitto, John, ed. Entry for 'Discerning of Spirits'. "Kitto's Popular Cyclopedia of Biblical Literature". https://www.studylight.org/encyclopedias/eng/kbe/d/discerning-of-spirits.html.

Bible Encyclopedias Discerning of Spirits

Kitto's Popular Cyclopedia of Biblical Literature

Bible Encyclopedias
Discerning of Spirits