“He descended to the dead.” We say those words almost every Sunday as part of The Apostles’ Creed, but what do they mean? My explanation has always been that they signify that Jesus was really dead. But now you don’t have to take my word for it. Here’s Oxford scholar Allister McGrath in his book I Believe: Exploring the Apostles’ Creed:
“He descended to the dead.” What does this mean? It is a statement of the belief that Jesus really did die. For the New Testament writers, Christ was not raised “from death” (an abstract idea) but “from the dead.” . . . The Greek term literally means “out of those who are dead.” In other words, Jesus shared the fate of all those who have died. . . . Jesus really was human like us. His divinity does not compromise his humanity. Being God incarnate did not mean he was spared from tasting death. He did not merely seem to die; he really did die and joined those who had died before him. 
He descended to the dead. Jesus really did die, but, of course, that was not the end of the story.
 Allister McGrath, I Believe: Exploring the Apostles’ Creed (Downers Grove, Illinois, 1997), Kindle, 61.