"David Did Not Ascend To Heaven"

Even if there was conscious experience in Sheol/Hades rather than its Biblical unconsciousness (Ecclesiastes 9:5-10, Psalm 88:10-12), according to the Bible, absolutely no one is in hell right now.  Hades is thrown into hell, the lake of fire, after the wicked are resurrected to conscious experience and bodily life to be annihilated (Revelation 20:13-15, Matthew 10:28, 2 Peter 2:6).  Until the first general resurrection of the dead (Revelation 20:4-6), which might only apply to the righteous/saved who perished during the reign of the beast of Revelation 13, servants of God and Christ are also not in heaven.  It is ambiguous within Revelation itself if all the righteous are resurrected together in the restoration of Revelation 20:4-6 or if the others return to life along with the wicked for judgment before God's throne in Revelation 20:11-15.  What is not as shrouded is what the Bible teaches about the intermediate fate of those who have committed to Yahweh or Christ in rationality, repentance, or righteousness.  Did the unconsciousness after death before resurrection end prematurely for those devoted to God and the morality rooted in him?

As Peter says, "David did not ascend to heaven" (Acts 2:34).  The context is one where the death and physical burial of David has already been addressed in Peter's speech (2:29).  While alone it could point to David having not ascended to heaven merely before he received the revelation that "the Lord said to my Lord: 'Sit at my right hand until I make your enemies a footstool for your feet'" (2:34-35), as opposed to him having not gone to heaven after death, the Old Testament and Jesus both teach that this had not occurred.  The collective dead were and are unconscious or nonexistent (Ecclesiastes 9:5-10), the righteous and the wicked alike (Job 3:11-19).  While it would be logically possible for God's people to be roused from this state to be at his side while the unrighteous "sleep" in death until their resurrection, this does not have to be the case for Paul's doctrine that death brings Christians to Christ's presence (Philippians 1:23-24) to also be true: for those resurrected, an enormous amount of time passing in a dreamless sleep or while phenomenologically nonexistent would not seem like more than one swift moment.

Jesus also affirms that at least by the time of his ministry, not even the righteous had moved from the unconscious condition of the dead in Sheol to be in heaven (John 3:13).  "'No one has ever gone into heaven except the one who came from heaven--the Son of Man'" are the words he uses only three verses before his much more famous statement in John 3:16.  If true, this would logically necessitate that not even the prophet Elijah was actually brought to heaven in the sense of New Jerusalem or to God's most direct presence as some Christians might think.  Certainly, this would require that David, like other figures ultimately aligned with God in righteousness or repentance despite their faults, was not in a paradise with Yahweh at that time.  If this continued, as the overlapping teachings of soul unconsciousness and the resurrection of the dead (Daniel 12:2) address, then David was still not in heaven by the time Jesus had resurrected and ascended.

No, he was not.  As Job says, the Biblical teaching is that not even the righteous would have an afterlife until "the heavens are no more" (Job 14:11-15).  People die, they are at "rest" in the sense of having no conscious experience, including pain (again, Job 3:11-19), and then God will rouse them "from their sleep" (14:12) to renew their bodies and restore consciousness to them (14:14-15, and also see Daniel 12:2).  Though the Old Testament does not specify that it would occur in a lake of fire, the consciousness of the wicked is already said in Ezekiel 18:4 to be rescinded a second time as just punishment--in a second death (Revelation 20:15).  The righteous alone inherit the eternal life that is not intrinsic to humanity, but to God (1 Timothy 6:15-16) and by extension to all beings God allows or wants to partake in this state along with him (Romans 2:6-8).  It is justice and not mercy that makes eventual nonexistence the cosmic penalty for sin (Romans 6:23), and during the wait for the various resurrections of the dead, there is not an experience of hell or heaven, or even experience at all in Sheol.