In these verses we see the child going out to the field to visit his father among the reapers. Suddenly, he cries out, "My head! My head!" (verse 19). His father, seeing the seriousness of the situation, instructs his servant to carry the child to his mother, but after a few hours sleeping on her lap, the little boy dies (verse 20; the Septuagint translates this as "he slept on her knees").
Though the details are scanty, most commentators suppose the child falls victim to sunstroke, a heatstroke caused by direct exposure to the sun. Out in a field of grain, the boy must not have had any protection from the intense rays of the Mediterranean sun. Being a child, he succumbs quickly, feeling the first symptom as a massive headache before fainting.
Spiritually, this diagnosis makes sense. Paul writes in Ephesians 6:16 that a Christian can stand firm in God's way if he is properly equipped, "above all, taking the shield of faith with which [he] will be able to quench all the fiery darts of the wicked one." Satan throws multiple distractions, trials, and ideas at God's children, and without the strength of faith, these can quickly and easily engulf us and make our heads spin. Without protection, their intensity could take our eternal life!
The Bible frequently speaks of spiritual lethargy and apostasy in terms of disease. He says of Judah, "The whole head is sick, and the whole heart faints. From the sole of the foot even to the head, there is no soundness in it, but wounds and bruises and putrefying sores" (Isaiah 1:5-6). David writes, "There is no soundness in my flesh because of Your anger, nor is there any health in my bones because of my sin" (Psalm 38:3). Jesus uses this metaphor as well: "Those who are well have no need of a physician, but those who are sick. I did not come to call the righteous, but sinners, to repentance" (Mark 2:17). Most telling is Christ's instruction to the spiritually blind Laodicean church to "anoint your eyes with eye salve, that you may see" (Revelation 3:18).
Applying this biblical metaphor to the events of II Kings 4, the boy, representing the individual Christian, falls prey to prolonged exposure to Satan's world. Since the tender, inexperienced child is unprepared for the onslaught of such a powerful and intense foe, the Devil easily overcomes his resistance, and his mother can only watch her child die in her arms. How many of our former brethren have we helplessly watched "die" in the arms of the church in recent years?