When a person dies they are dead! That is, they are no longer an “embodied being”.
It doesn’t matter that something identifiable as us survives the dissolution of the physical body; the Bible says we are “dead”. Until we are re-embodied we are “dead”. Death robs a human of “soul” life—that is life as we experience it here in this world, life that we share with animals and is subject to creaturely weakness, aging, decay and cessation. Paul speaks of our bodies as natural bodies (he uses the word psuche—“soul”). By this I take it that he means a body suited to our current mode of living.
The Old Testament (OT) and New Testament (NT) words that translators render soul are used to cover many things. Sometimes the entire person, or life, the invisible force that produces movement/life in the body or the heart, feelings, longings, the emotional capacity of a person, or the mind and now and then they are used as equivalent to the word spirit (which itself is used in numerous ways). The above and more is common knowledge and you only have to use a concordance to see that for yourself. We’re not to think of soul or spirit as material substances. The words are used as different aspects of a single person. When Paul prays that the young believers may be preserved blameless and speaks of their body, soul and spirit (1 Thessalonians 5:23-24) he doesn’t have independent substances or “compartments” in mind but various aspects of them as persons. Jesus speaks of our loving the Lord our God with heart, soul, strength and mind (Mark 2:30) but He isn’t speaking of different compartments, much less “substances” in a person.
Life after death is a reality (if I’m understanding correctly the implications of Philippians 1:23 and 2 Corinthians 5:1-8; Luke 23:43). But the one who is with the Lord is nevertheless dead—the unity of the person has been distrupted and God did not create us to be ghosts but embodied humans and Jesus is the model of what God eternally purposed for humans (see Philippians 3:20-21; Romans 8:23 and elsewhere).
The Sadducees did not believe in spirits or angels or resurrection (Acts 23:8, a text that is trickier than it looks). In Matthew 22:23-33 Jesus dismisses their ignorance by implying that there is life after death and therefore there must be a resurrection. Some religions believe in life after death but deny resurrection to immortality. Jesus argument is not based on the present tense am because that wouldn’t deal with the pointed objection of the Sadducees. Jesus (so I judge) is clearly leaning on the truth that God made promises to Abraham and his descendants which could never be fulfilled if humans died and that was the end of them. If that were true God would eternally be God over the dead since He will be there when the entire human race at some point will be dead (Hebrews 9:27, perhaps?). But underneath that, Jesus believes that God is faithful and adequate. If He made promises He will keep them even to those who are now dead (see Acts 2:29). But He cannot keep them to those who died and were “gone” therefore there must be a resurrection. Note Romans 14:7-8 and Acts 17:28 for further reflection.
Our loved ones who have died are indeed dead but they died trusting and living unto God and God is faithful (Titus 1:2). There’s a new day coming, a new world coming in fullness, a new world and a new day that has already begun in and through the resurrected, immortal and glorified Jesus of Nazareth, who was alive, became dead and is alive or evermore and has the keys of Death and Hades. Jesus’ glorious resurrection is the assurance of our coming glorious resurrection and His indwelling in His People through and as the Holy Spirit is also our guarantee.