If the dead are already in heaven, how do they rise at the second coming?

Believers will join Moses and Elijah and the other saints in Heaven with our father when our bodies die. Our soul and spirit fellowship with God in paradise. However when the "Day of the Lord" comes we will be clothed with our new immortal bodies to complete us, just as Jesus was clothed with his new body and was the first fruit of the new breed of immortals in Christ. When he returns we will all be changed and clothed with these new bodies. That is the first resurrection. By the way, unbelievers will also be resurrected in the same manner and clothed with their determined immortal bodies but much later. On the Day of the Lord the angels will gather the elect from the 4 winds those who are raptured for the coming Battle of Armageddon. This will occur on Rosh Hashanah (Festival of Trumpets) and will take until Yom Kippur 10 days later when the day of Atonement happens and the Battle of Armageddon. The marriage supper of the Lamb takes place immediately after. Unlike what we westerners like to think about "marriage suppers" as a feast or celebration for us, the only ones who will be feasting will be the birds of the air on the flesh of those who are slain during this great battle.

The assumption is that the dead - depending on their station in life - are in heaven or in a fiery hell. Does this make sense against the pattern of Jesus' teaching and the events of the resurrections he performed?

When Jesus resurrected Lazarus, where was Lazarus when he died? In heaven? No! According to John 11:11 and John 14:14, Lazarus had been dead for several days and had already begun to decay. Lazarus was on earth and in the earth (his grave). So he was not in heaven. And, when Jesus resurrected Lazarus it was back to life on earth. Additionally, when Lazarus was resurrected, he did not report being in heaven (or in a fiery hell). Certainly if he was in any of those places, he would have surely said something about it. Reason why is because the dead are not conscious of anything. Not conscious of passage of time, pain, heat, cold, etc. (Eccl 9:5,10)

King David is reported at Acts 2:34 as never ascending into heaven. So where is he? His his grave awaiting the promised resurrection at John 5:28-29.

By his own words, Jesus said that no one on earth has EVER gone to heaven except the one who came from heaven and had died and ascended back into heaven. (John 3:13)

If - as Jesus taught at Matthew 6:10 - that God's Kingdom is coming DOWN to the earth, why is there a need to go UP to heaven?

The confusion in this matter is caused by the religious system called by men - Christianity. It insists on persons listening to it rather than obeying God at Luke 9:35 who commanded that we listen to His Son.

Abstract

The idea that the saved go to heaven when they die is somewhat anachronistic. Equally anachronistic is the idea that people will be "raptured" into heaven when Jesus returns. Paul had another meaning in mind when he wrote this verse.

N. T. Wright explains in Surprised By Hope:

The word parousia occurs in two of the key passages [concerning rapture theology] in Paul (I Thessalonians 4:15 and I Corinthians 15:23), and is found frequently elsewhere in Paul and the New Testament. It seems clear that the early Christians knew the work well, and knew what was meant by it. People often assume that the early chruch used parousia simply to mean "the second coming of Jesus" and that by this event they all envisioned, in a quite literal fashion, the scenario of I Thessalonians 4:16-17 (Jesus coming down on a cloud and people flying upward to meet him). Neither of these assumptions is in fact correct.—p. 128

Wright then explains the two meanings of parousia that were in play:

1. "The mysterious presence of a god or divinity, particularly when the power of this god was revealed in healing." (p. 129)

2. "When a person of high rank makes a visit to a subject state, particularly when a king or emperor visits a colony or province." (p. 129)

As Wright explains it, Paul envisioned Jesus returning to earth to establish His everlasting Kingdom here, not in heaven. Therefore, the spirits of the already dead will return to inhabit their resurrected bodies and the bodies of the living will be transformed so that we can meet our King.