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)
The author of Hebrews was pastorally remonstrating his congregation for their lack of maturity. They had been Christians long enough that they should be able to teach others, but they themselves were still in need of remedial education. The telltale sign of spiritual maturity, he notes, is discernment. Blogger Tim Challies defines discerment as "the skill of understanding and applying God's Word with the purpose of separating truth from error and right from wrong." The benefit of maturity via discernment is stability in life. Church fads come and go and self-proclaimed prophets rise and fall, but the spiritually mature person can distinguish between what to accept and what to avoid by testing everything by the word of God.