Merriam-Webster: the quality of being able to grasp and comprehend what is obscure.
"Discernment is the process of making careful distinctions in our
thinking about truth.
First Thessalonians 5:21-22
teaches that it is the responsibility of 
every Christian to be
discerning: "But examine everything carefully; hold fast to that which
is good; abstain from every form of evil."
The apostle John issues a
similar warning when he says, "Do not believe every spirit, but test the
spirits to see whether they are from God; because many false prophets
have gone out into the world" (1 John 4:1).
Without it, Christians are at risk of being "tossed here and there by waves, and carried about by every wind of doctrine" (Ephesians 4:14)." GraceToYou