There is dead in spirit, then there is dead in body. Jesus brings Life to the dead spirit. Later, there is the bringing life to the dead body. The Life in the dead human spirit happens when you believe on Him as your Savior. It happens while you are still in a body under the sentence of death physical.
In Thessalonians, Paul relates a time when the dead in Christ shall rise, then we who are alive and remain will be caught up together with them, changed in a moment, in the twinkling of an eye. So there will be a moment when even those still in a body and physically alive will be 'translated'. But ONLY if they are spiritually alive by His Spirit Life within their human spirit.
Show me some scriptures that indicate that there is such a thing as a dead spirit. I read that a body without a spirit is dead:
Jas_2:26 For as the body without the spirit is dead, so faith without works is dead also.
I also see that the death and resurrection of Christ is characterized as being dead physically and being alive again through the spirit:
1Pe_3:18 For Christ also suffered once for sins, the just for the unjust, that He might bring us to God, being put to death in the flesh but made alive by the Spirit,
I see the same future promise given to believers:
Rom_8:11 But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ from the dead will also give life to your mortal bodies through His Spirit who dwells in you.
I see that even with the spirit of Christ in us our bodies are still dead. But no such thing as a dead spirit.
Rom_8:10 And if Christ is in you, the body is dead because of sin, but the Spirit is life because of righteousness.
So what exactly do you mean by dead in spirit?