First Peter is concerned primarily with how believers are to endure suffering, and in the context of this instruction Peter encourages us, like newborn infants, to “long for the pure spiritual milk,” that by it we “may grow up into salvation” (2:2). Peter’s injunction does not deny the emphasis in other portions of Scripture on our need for solid food, those more complex biblical doctrines that are grounded upon the basic truths of the gospel (Heb. 5:11–14). Instead, the apostle wants to make sure that we imbibe repeatedly the elementary teachings of our Lord even as we digest those things built upon these basic truths. After all, mature adults include both solid foods and milk in their diet, and so we must consume our spiritual milk as we graduate to the meat and potatoes of apostolic and prophetic teaching.
Not only are we to drink in the basics of the gospel, we are to rejoice in our Lord’s elementary teachings, as we see in today’s passage. After being sent to preach the gospel and heal the sick (Luke 10:1–12), seventy-two disciples of Jesus return to Him and are overjoyed at their ministry’s success, especially in the fact that the demons are subject to them in the name of Christ (v. 17). Yet Jesus does not tell them that they should rejoice in the success of their outreach, even though He acknowledges the results of their ministry and the authority He has delegated to them (vv. 18–19). A Christian’s joy must instead be in that which is more fundamental — the fact that the name of every believer is written in heaven (v. 20). The source of all true joy is found in the free forgiveness Christ has purchased for us on the cross.
Unconsciously, many of us have absorbed the culture’s preoccupation with outward success, and so we find it difficult at times to be ever joyful on account of the simple gospel. Success and power are not inherently evil, but we can pursue them more out of a desire to satisfy our sin than to honor Jesus. In other words, the pleasure such things bring can be at our souls’ expense. We must be careful when rejoicing in the often temporary pleasure of success not to forget the eternal pleasures that are rooted in our justification through the atoning death of Christ. If we are taking excessive joy in outward success and not that we are righteous in Jesus, we must return to the cross in repentance and rejoice in His great gift once more (1 John 3:19–24).