The book of Hebrews, as it unfolds week by week in our bible study, is revealing the pastoral love and concern of the writer’s heart for his people. They are already experiencing some degree of persecution, which will only be getting worse. The author of this sermon letter knows that if his people are not firmly anchored in their faith and in the knowledge of Christ, the persecutions to come may at least cause undue spiritual distress and at worst drive them from their faith altogether. And so by turns he warns and encourages his readers (and us) to avoid the perils of shallow faith by growing in the grace and wisdom of the knowledge of the Lord.
Up until the end of chapter five, the warnings have been general in nature, but when we reach 5:11 we find a rebuke not only stern, but also personal.
“. . . you have become dull of hearing. For though by this time you ought to be teachers, you need someone to teach you again the basic principles of the oracles of God. You need milk, not solid food, for everyone who lives on milk is unskilled in the word of righteousness, since he is a child. 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 5:11–14
His readers, though not new to the faith, haven’t grown beyond infancy in the knowledge of God, and their powers of discernment are therefore weak and ineffective. Though by now they ought to be able to teach others, they are perilously immature.
Now, even an immature Christian is still a Christian and safe in her Father’s omnipotent grasp. Immaturity isn’t fatal to faith. And true faith is no more or less genuine in mature believers than in immature believers. But the coming storms of persecution will be far more difficult to weather for those who are infant believers. Those who are unskilled in “the word of righteousness” are more liable to be “tossed to and fro by the waves and carried about by every wind of doctrine, by human cunning, by craftiness in deceitful schemes” (Eph. 4:14). Moreover, they will be unable to help stabilize their brothers and sisters in the faith when the storms come. How can we encourage one another when we can’t find our own footing?
Of deeper concern is that immature believers may, to our eyes, be indistinguishable from unbelievers. Which leads to one of the most severe warnings in the entire New Testament, one which we are wise to consider carefully.
For it is impossible, in the case of those who have once been enlightened, who have tasted the heavenly gift, and have shared in the Holy Spirit, and have tasted the goodness of the word of God and the powers of the age to come, and then have fallen away, to restore them again to repentance, since they are crucifying once again the Son of God to their own harm and holding him up to contempt. For land that has drunk the rain that often falls on it, and produces a crop useful to those for whose sake it is cultivated, receives a blessing from God. But if it bears thorns and thistles, it is worthless and near to being cursed, and its end is to be burned. —Hebrews 6:4–8
This seems, at first blush, to describe genuine believers who have fallen away from the faith. But if we keep our bearings, considering the flow of the author’s argument and the surrounding context, we will see that this passage does not contradict our Lord’s promise that the sheep to whom he gives eternal life will never perish and nobody is able to snatch them out of the Father’s hand (Jn. 10:27–29).
From the first chapter of Hebrews, the warnings against unbelief have been soundly supported by Old Testament scriptures, particularly the account of the wilderness generation who fell in the desert before reaching the promised land because of their unbelief. With the warning against hardened hearts of unbelief from Psalm 95 in the background (3:7–11, 15; 4:3, 5, 7), the parallels with the wilderness generation aren’t difficult to see in the warning now before us. The congregation of the people of Israel who left Egypt with Moses all experienced the blessings of the exodus. Every Israelite who followed Moses out of Egypt was free from slavery, was protected by the cloud by day and the pillar of fire by night, ate the manna, drank the water from the rock, heard the word of God (at times, audibly, with their own ears!), and enjoyed the blessings of living under God’s covenant. Yet, as our author has made abundantly clear, the vast majority of the Israelites were unbelievers—even while they enjoyed the blessings and the presence of the Lord. The Lord therefore declared that they would not enter his rest, and they died in the wilderness.
This is the same point being made in chapter six, verses 4–8. There are people in our churches who profess to believe in Jesus, and they enjoy the many blessings of living among the covenant community of Christians, yet they are not born-again, Spirit-filled believers. They may have an intellectual understanding of who Jesus is and the facts of the gospel, but they aren’t trustingly believing in Jesus. For unbelievers to walk away from the church is not only natural, it is expected (1 John 2:19). And when they do walk away, after experiencing the blessings and sitting under the preaching of the word, with their hearts hardened to the truth, this passage tells us that it is impossible to restore them to repentance, “since they are crucifying once again the Son of God to their own harm and holding him up to contempt” (6:6).
Realizing that nothing is impossible with God (Luke 1:37): “We are not able to restore them, but that doesn’t mean that God cannot. Indeed, as long as the gospel goes forth, we should never despair of its power to save anyone.” Nevertheless, we must take this warning seriously. The writer of Hebrews issues this warning to his people who haven’t matured in their faith because if they don’t care to grow in their faith it’s an indication that they need to soberly reflect on the condition of their hearts. And the same is true for us today. This is a call not for hateful judgmentalism, but for loving discernment. Christians, if we don’t care to “attain to the unity of the faith and of the knowledge of the Son of God, to mature manhood, to the measure of the stature of the fullness of Christ” (Eph. 4:13); if we are satisfied with a spiritual diet of milk and don’t hunger for the meat of the word, we ought to be concerned about the health and even the genuineness of our faith.
Richard Phillips shares two implications and a final consideration which flow from this text:
“The first has to do with the nature of true and saving faith in Jesus Christ. Mere knowledge of the gospel is never enough. Understanding and even intellectually affirming Christian teaching is insufficient for salvation. As important as doctrine is, as important as knowledge of Scripture is, it is personal knowledge of and trust in Christ that alone constitutes saving faith.
. . . . A second implication is that the test of our faith is the fruit that we bear. Surely that is how this passage fits into the context of the overall letter. The author has been exhorting his readers to press on to maturity and now he warns them that a failure to do so calls into question the reality of their conversion. How do we know someone is truly converted? We know not merely because he is made a profession of faith but because the power of the gospel bears fruit under trial.
. . . . If you are content with merely drinking in the rain, but not concerned to honor God in your life, if you were unable or unwilling to hold fast to God and praise his name in times of trouble, then that is a very alarming sign that ought to provoke fundamental reflection regarding the state of your soul.
. . . This leads to a final consideration. What does this passage say about the idea of eternal security and assurance of salvation? The first answer is that it ought to make our statements more careful and sober. The picture here is a somber one. It depicts professing believers, probably church members, who are not really saved but fall away into a hopeless state. Therefore as Andrew Murray puts it, ‘My assurance of salvation is not something I can carry with me as a railway ticket or a banknote, to be used, as occasion calls. . . . My assurance of salvation is alone to be found in the living fellowship with the living Jesus in love and obedience.’
. . . . Assurance is something that comes from the knowledge of God and of his promises, and is thus the result of the exercise of faith. The same is true of security; It is through faith alone that we are ever secure. Security comes from trusting in Jesus Christ, from persevering to the end in the power of the Lord.”
This post is already awfully long, so I will break here. But I’ll follow up with a second post (part 2) in order to finish what is covered in our lesson, which gives us a solid anchor for assurance of faith. These passages are too important to skip quickly across. Thank you for your patience.
 Richard D. Phillips, Hebrews: Reformed Expository Commentary, (Phillipsburg, NJ: P&R, 2006), 192
 Murray, Holiest of All, 209. (emphasis mine)
 Ibid. 194-196