Being dead doesn't mean we cease to exist. Dead or alive refers to the condition of our soul's relationship to God. God has power over the life and death of the soul through the sacrifice of Christ on the cross.
The bad news is that you, your own self, can't keep your soul alive. The good news is that it can be kept alive through faith in Jesus Christ.
Paul's writing to people who are metabolically alive and telling them that they were dead and now they're alive, clearly he's not talking about their bodies, he's talking about their souls. We've identified two states of the soul.
Passing from death to life is referred to as being quickened, q. We're quickened when we put our faith in Jesus Christ. It's also called being saved, or "born again."
It's possible to write the gospel of salvation through faith in Jesus Christ as a physical formula, but that's just algebra, can we prove a real-world connection between Physics and the Bible?
All souls are eternal, however, they're either dead or alive. The death of our body isn't the end of consciousness, and the death of our soul isn't the end of existence. We're made alive through Jesus Christ.