Which part of a person is immortal, the body or the soul/spirit?

Les explains that resurrection is not just being brought back to life; it is that unique, sovereign act of God whereby He brings back from the dead a human being who has died, not to die again, but to a life of eternity. He stresses that when God breathed into man's nostrils the breath of life, and man became a living soul, that separated man from all other categories of life, because man is immortal in the area of the soul. The body is not immortal, but the soul or the spirit is, and those two are so closely connected that they are almost used together. That is why Revelation speaks of the resurrection of the just to a life of immortality in God's presence. The lost are resurrected to a life separated from God, or the second death, but they still continue on through all eternity. Les notes that some groups disagree, teaching that when a lost person dies they are annihilated, but that does not line up with Scripture. Instead, the lost will suffer, experience regret, and experience feeling throughout all the eons of eternity. Christ was the first person to ever experience resurrection, which is why He is called the first fruits, plural, of them that slept.