“And you were dead in your trespasses and sins” (Ephesians 2:1).
This is one of the most important verses in all of Calvindom. The classic reading of this text has always held that unbelievers are dead in their sins. This was true of us. As unbelievers, we were dead and could not respond to the gospel. The Holy Spirit regenerated us, and then we responded in faith. This is Calvinism 101.
Federal Visionists claim to believe all of this, but do not be duped by their assertions of orthodoxy. Federal Visionists argue that Paul was speaking of death as a metaphor, not as a literal reality. Thus, unbelievers are not literally dead. Rather, Paul used death as a metaphor to describe how radically unbelievers are separated from God: it is as if they are dead. Obviously, this implies that regeneration is also not a literal reality, but only a metaphor for how radical the change is from unbeliever to believer.
Conversely, the Reformed faith has always insisted that Paul was speaking of literal death. Unbelievers are literally dead. They are corpses. They need literal regeneration. They need to be brought back to life, literally.
Of course, unbelievers are not really dead. Their bodies are alive. Their souls are alive, too. What part, then, of an unbeliever is dead?
The Reformed faith has always insisted that unbelievers are dead spiritually, that is, their spirits are dead. Man has three constituent parts: body, soul, and spirit (Hebrews 4:12). The bodies and souls of unbelievers are alive, but their spirits are dead. Regeneration is the literal resuscitation of their spirits. Thus, trichotomy becomes a key weapon in fighting the Federal Vision heresy.