Originally Answered: Is it possible to have the gift of discernment and not use it?
When the Bible talks about discernment — when it talks about assessing spiritual things — it's talking about a rational assessment based on objective criterion. You can't be "too much in your head" when it comes to spiritual discernment. Using your head is spiritual discernment, if you're using the truth properly.3
Spiritual discernment is a pursuit that must always engage the mind. We discern truth from error and right from wrong by using our minds to search Scripture, to recall Scripture, and to compare everything to Scripture. Without the Bible and its objective truths there can be no discernment.
Scripture repeatedly shows this correlation between discernment and knowledge, between discernment and a mind that is saturated with and shaped by the Bible. In Psalm 119:66 the psalmist writes, "Teach me good judgment and knowledge, for I believe in your commandments." The words translated "good judgment" could as easily be translated "discernment" and, indeed, are rendered that way in certain translations.4
Philippians 1:9 says similarly, "And it is my prayer that your love may abound more and more, with knowledge and all discernment." And again in Proverbs 16:21 we read, "The wise of heart is called discerning," and in Proverbs 15:14, "The heart of him who has understanding [the discerning person] seeks knowledge, but the mouths of fools feed on folly."
The evidence continues to mount in Proverbs 18:15 where we read, "The discerning person acquires knowledge" (NET), and Proverbs 19:25, which says, "Strike a scoffer, and the simple will learn prudence; reprove a man of understanding [a discerning man], and he will gain knowledge."
The testimony of Scripture is plain: While spiritual discernment is a practice that is absolutely dependent upon the work of the Holy Spirit, God has so ordained that it is also a discipline that relies on the mind.
The purpose of discernment is to further the chief end of man, the foremost reason we exist, which, to borrow the words of the Westminster Shorter Catechism, is "to glorify God and to enjoy him forever."5 By being people of discernment, we bring glory to God and learn to enjoy him ever and ever more. Conversely, if we refuse to exercise discernment and are swayed by every wind of doctrine, we deny him the glory that is rightly his and do not learn to enjoy him more.
We will not always need to exercise discernment. Discernment is a discipline necessary only in a world in which we are faced with sin and temptation.
When God created Adam and Eve, he made them sinless and yet with the ability to choose between good and evil. Tragically, they displayed poor discernment, falling for the wiles of the Devil and bringing sin into the world. We live now between the beginning and the end, and, though it is now impossible for us to go through life without sinning, we make decisions moment-by-moment and day-by-day in which we use discernment to attempt to separate what is right from what is wrong and what is true from what is false so that we can bring glory and honor to God.
But when Jesus Christ returns and this world passes away, the need for discernment will also pass away. In heaven we will no longer be able to sin. There will be no error, no wrong for us to fall prey to. We will no longer need to be discerning and will no longer have to test and try what we do and what we believe. Discernment is a process that prepares us for heaven and enables us to eagerly await the end of discernment.
Thus we see that discernment begins and ends with God. God provides the ability to know Him and to make decisions that please Him so that we may serve him and bring glory to His name. Biblical discernment is always, ever, and innately a spiritual task.
To think biblically about life, we must be willing and able to make clear distinctions between God's ways and all other ways. We must be willing to think deeply about issues and to dedicate time and effort to learning what is right and what is wrong. We must also be willing to grow in our knowledge of God and of the Bible, for this is where we will learn of God's ways.