Let your speech always be gracious, seasoned with salt, so that you may know how you ought to answer each person. (Colossians 4:6 ESV)
But solid food is for the mature, for those who have their powers of discernment trained by constant practice to distinguish good from evil. (Hebrews 5:14 ESV)
See to it that no one takes you captive by philosophy and empty deceit, according to human tradition, according to the elemental spirits of the world, and not according to Christ. (Colossians 2:8 ESV)
For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and of spirit, of joints and of marrow, and discerning the thoughts and intentions of the heart. (Hebrews 4:12 ESV)
Beloved, do not believe every spirit, but test the spirits to see whether they are from God, for many false prophets have gone out into the world. (1 John 4:1 ESV)
But even if we or an angel from heaven should preach to you a gospel contrary to the one we preached to you, let him be accursed. (Galatians 1:8 ESV)
Do not judge by appearances, but judge with right judgment. (John 7:24 ESV)
And it is my prayer that your love may abound more and more, with knowledge and all discernment, so that you may approve what is excellent, and so be pure and blameless for the day of Christ, filled with the fruit of righteousness that comes through Jesus Christ, to the glory and praise of God. (Philippians 1:9-11 ESV)
Brothers, do not be children in your thinking. Be infants in evil, but in your thinking be mature. (1 Corinthians 14:20 ESV)