The question itself suggests the difficulty we have in making the distinction between physical and spiritual death in Scripture. Sometimes the Scriptures themselves do not draw the lines clearly between physical and spiritual death. For example, it seems that in Romans 5:12–15 physical and spiritual death is one reality—physical death being the outward expression of spiritual death, the separation and estrangement of a person from God. Nonetheless, several principles may help as we try to recognize when and where the Scripture is making the distinction between these aspects of death.
First, read the Scripture in its plain and normal sense. Hebrews 9:27 declares: “Man is destined to die once, and after that to face judgment.” If we take this verse in its plain and normal sense, it is clear that the kind of death under consideration is physical death—the separation of the soul and spirit from the physical body. Ephesians 2:1 says, “You were dead in your transgressions and sins.” This passage describes the condition of a Christian before salvation. The condition was spiritual death, separation from God.
Second, pay attention to the context in which the word death is used. The meaning of a word cannot be divorced from its context. The Lord commands Adam not to eat of the Tree of Knowledge of Good and Evil and then gives him a warning: “When you eat from it you will surely die” (Gen. 2:17). When Adam and Eve disobeyed God in Genesis 3, they do not die immediately in the physical sense. They died immediately in a spiritual way. They became separated from God spiritually even though the inevitable consequential seeds of physical death were sown in their act of disobedience (Gen. 3:19). Context clarifies the meaning of death in Genesis 2:17.
Third, pay attention to words in the passage that qualify or describe the concept of death. In Revelation 20:14–15 the lake of fire, the eternal destiny of the lost is called the second death. The reader should note that the Holy Spirit refers to this death as the second death and further describes it as the lake of fire. The second death in this passage is eternal separation from God. When a person dies physically in a spiritually dead condition, that person’s spiritual death becomes permanent.
At the same time we must recognize that sometimes there is overlap in meaning between physical and spiritual death. Remember, too, that our study of Scripture must be more than an academic exercise. The terrible fact that people who die without Christ will be lost forever in conscious suffering should move us to tears, to deeper commitment to Christ, and to more informed zeal in evangelism.