1. Life and Death are not Essential Properties of Being Human
The predication of attributes to a logical subject implies a distinction between the subject itself and that which is predicated of it. This is evident when we are comparing two otherwise identical subjects, as in the case of identical twins. How a is differentiated from b, therefore, underscores the underlying essential identity of a and b. This is true whether we are comparing two radically different genera or two species of the same genus. In the case of humans, the predication of attributes to a and not to b indicates their genetic identity. Thus, the propositions “John is dead” and “James is alive” imply that death and life are not essential properties of being human. What it means to be human, in other words, is not changed by whether life is predicated of James or death is predicated of John. The living human and the dead human are, irrespective of their non-essential differences, one in their humanity. We should not pass over this point lightly as if it were some obscure point of metaphysics. This is a basic logical point to be insisted upon: If we can simultaneously predicate x and ~x of two genetically identical logical subjects, then neither x nor ~x are essential to the ontology of the logical subjects in question. John and James remain human, but the state in which they remain differs.
2. Man’s Essential Attribute is His Intellectual-Moral/Covenantal Relationship to God
If life and death are not essential properties of man, and they are not, then what property or properties are essential to man? Man’s creatureliness is essential to man, for all things other than God have been created by God. Man is other than God. Therefore, we must predicate creatureliness of man necessarily. Yet all living things other than God are creatures of God, thus man must be differentiated from every other non-God thing. And the unique relationship that man has to God among all of God’s creatures is this: Man is the image of God. For man to be, therefore, is for man to be the image of God. Living men and dead men stand in relation to God as living or dead, elect or reprobate, more faithful or less faithful to their vocation as believers or unbelievers invested with creaturely responsibilities and corresponding talents.
As the image of God, man is a thinking, willing, moral agent. Here we must note that man’s responsibilities can be either essential or accidental. Essentially, man must think, will, and act according to moral standards. Accidentally, man must do these things within given boundaries predetermined by God in his Sovereignty. By virtue of his being – as being-in-relation-to-God – man is responsible for his thoughts, choices, and actions. By virtue of his individual existence, man is responsible for his thoughts, choices, and actions under existential conditions unique to him (e.g. the constitution of his body, his intelligence, the time period into which he has been born).
To be a human is to stand in relation to God as his creaturely image bearer; to be the image of God is to be a thinking, willing, moral agent. Man is, essentially, one who stands in relation to God as a thinking, willing, moral agent. Consequently, while man may be either dead or alive, these states have no bearing on whether or not he exists, for they are accidental properties, whereas he is essentially a creature who stands in relation to God as a thinking, willing, moral agent. Now, in killing the wicked God is rendering them dead. Scripture is clear on this point: The wages of sin is death. Since death is merely an accidental property of human beings, and thinking, willing, and engaging in moral behavior is essential to being human, it follows that those whom God renders dead remain thinking, willing, moral agents, for they remain human.
3. God Alone is One in His Being and Attributes
Theological orthodoxy affirms that God and his attributes are One. That is to say, God is essentially simple, independent in the fullest expression of the term. God is not composed of parts, and therefore he cannot cease to have life, for in not having life he would no longer possess an essential property of his being. Consequently, God would not be God but something else. This is, of course, impossible. Therefore, we rightly recognize that life is not a state of being which God participates in; rather, God is life itself. If God did not have life, he would cease to exist/be God.
However, this is not the case with humans or any other creature capable of living and/or dying. A non-existent thing has no states of being which may be predicated of it; however, if life or death are predicated of a creature, then that creature exists necessarily. What, then, is existence? Existence is the copula between a given logical subject and its attendant predicates. John and James do not correspond to actual humans, but it would self-contradictory to assert that they do not, therefore, exist. For if existence is the copula between a logical subject and its attendant predicates, and John and James are logical subjects, then they are the logical subjects of predication. The proposition “John does not exist” is self-contradictory, for John cannot be and not-be a logical subject of predication at the same time and in the same sense. Conversely, the proposition “John exists” is a tautology that merely states that John is a logical subject of predication.
Every logical subject, then, exists, for every thing exists. The question facing us, however, is how these subjects exist. What properties are essential to their ontology? What properties are accidental to their ontology? John and James are not essentially spiritual creatures made in God’s image, but are essentially conceptual entities which serve as representatives of spiritual creatures made in God’s image. Likewise, John and James are not body-soul composites, but are immaterial-conceptual entities. John and James are real insofar as they are immaterial-conceptual entities; they are the logical subjects of which we are predicating, respectively, life and death. They exist.
3a. Kinds of Existence
The proposition “The wicked will cease to exist” is, on this account, true if and only if the wicked will no longer even be the merely logical (i.e. purely conceptual) subjects of predication. This, however, isn’t possible, for God is omniscient. The wicked, therefore, necessarily will continue to exist as purely logical subjects of predication in the mind of God, at the very least. This “weak” kind of existence (i.e pure conceptuality) demonstrates that the wicked cannot cease to exist, for if they did this would imply that God is not omniscient. Additionally, if God at one point has knowledge of the wicked and later does not have that knowledge of the wicked, then he is not immutable.
 Metaphysically, the essential identity between two subjects is what makes them members of the same ontological set/class.
 Metaphor, simile, and analogy are literary devices that seek to reveal otherwise hidden points of univocality, the difference between these devices being their expressive power. “Man is a beast” and “Man is like a beast” express, at root, the same propositional content “Man and beast have x in common.” The metaphor “Man is a beast,” however, seeks to directly identify man as a beast and, therefore, has a richer expressive content suggesting that the difference between man and beast, although real, is overshadowed by man’s beastly behaviors.
 For a more detailed philosophical analysis of “existence” as a non-predicate, see “The Relevance of Kant’s Objection to Anselm’s Ontological Argument,” in Religious Studies 47 (2011), 345-357.