Hebrews 5:11

Of whom we have many things to say, and hard to be uttered, seeing ye are dull of hearing.

The many things hard to be uttered are deeper important truths about Christ, about His work as high priest, about the mystery of godliness, and about His power to save completely to the uttermost all who come to Him. To be dull of hearing is to be spiritually weak, with perceptions that are not sharp and acute, slow to discern the things of the Spirit and the working of the Spirit. The fault for this dullness lay with the hearers themselves rather than with their teachers.

Although abundant advantages and opportunities had been given them, they had not received in faith the earlier truths imparted to them and had not advanced onward and upward to improve their opportunity to learn more of themes of eternal interest. Because they were not ready to receive these truths, they were hard to explain and could not be spoken as plainly as desired, so that difficult instruction was hard to grasp and deeper teaching was beyond reach. This warning joins careful attention to Scripture with the need for a changed heart in order to discern error, since dullness of hearing makes spiritual teaching difficult to grasp.

Such dullness weakened memory so that truths essential to success in character building could not be retained, though rightly heard they would have been a savor of life unto life. Misconceptions left the hearers with an indistinct view of Christ's power to save and to make His people a praise in the earth. Such dullness leaves believers like infants and babes and stunted dwarfs in need of basic milk and basic instruction and unprepared for strong teaching.

This condition exactly pictures many of God's people today who have had every advantage and ought to be teachers saying, Here I am, send me. Yet they do not discern the value of Bible truth, they cannot bear the plain requirements of Scripture, they remain half Christians and half worldlings divided between Christ and the world, children needing milk, and they become hindrances instead of strength to the church. The verse therefore urges continued growing into Christ and active exercise of spiritual powers to discern good and evil. Reading this warning in chapters five and six joins it to heeding God's messages and growing in faith and love.