Discernment is essential in making wise decisions. It's in the Bible, James 1:5, TLB. "If you want to know what God wants you to do, ask Him, and He will gladly tell you, for He is always ready to give a bountiful supply of wisdom to all who ask Him; He will not resent it."
Discernment is essential for spiritual growth. It's in the Bible, Hebrews 5:14, TLB. "You will never be able to eat solid spiritual food and understand the deeper things of God's Word until you become better Christians and learn right from wrong by practicing doing right."
Discernment comes to those who are humble. It's in the Bible, Psalms 25:9, NIV. "He guides the humble in what is right and teaches them His way."
Spiritual things are spiritually discerned. It's in the Bible, I Corinthians 2:13,14, NIV. This is what we speak, not in words taught us by human wisdom but in words taught by the Spirit, expressing spiritual truths in spiritual words. The man without the Spirit does not accept the things that come from the Spirit of God, for they are foolishness to him, and he cannot understand them, because they are spiritually discerned."