...Is it through some kind of spiritual realm or do they wait for a specified time until he brings them up to heaven?
This is a question that has been debated over many years. In Revelation 20:4-5, the Apostle John tells us that certain people "came to life and reigned with Christ a thousand years. The rest of the dead did not come to life until the thousand years were ended. " This is known as the Millennium. Now, if you read verse 3, you also find out that an angel of God came down from heaven and "And cast [the devil] into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season."
How do we interpret this passage? Traditionally, there have been three accepted views. To be clear, each view has its merits. Because of the diverse views among many Jesus-loving, Bible-loving Christians, all three of the following views are acceptable.
1. Amillennialism: In this view, the church is already living in the millennium (i.e. there is no future thousand years). In fact, the "thousand years" is simply a figure of speech (i.e. should not be interpreted literally). The present age will continue until the return of Jesus, when there will be a resurrection of both believers and unbelievers. The bodies of believers will rise to be reunited with their spirits and enter into heaven forever. Unbelievers, however, will be raised to face final judgment. As I mentioned in my last sermon ("Servant - Part 2" Luke 22:24-30), believers will also stand judgment, but this judgment will be a judgment of service. God will judge how well and how hard we labored for his kingdom and give rewards accordingly.
2. Postmillennialism: In this view, Christ will return AFTER one thousand years. The present age of the church will continue as the power of the gospel gradually increases. More and more of the world's population will be Christians and subsequently, society itself will function more and more according to God's standards. This will usher humankind into a millennial age of peace on earth. Once this thousand years is over, Christ will return & believers and unbelievers will be resurrected to be judged accordingly.
3. Premillennialism: This view states that Christ will return BEFORE the millennium. When Jesus does return, he will bind Satan and rule on earth for 1000 years. At the end of this time, Satan will let loose, only to be destroyed by Jesus. Then comes the final judgment where believers and unbelievers are judged with the judgment of service and salvation respectively.
So there you have it. 3 views. If you're really serious about this topic, I'd recommend this site, which shows these views in graphic form. Also, use the search bar and type in "millennium."
Summarily, as a Christian, you can hold to any of the three views. There are both positive and negative results from holding to each of these views. For example, if you hold to the postmillennial view, one of the positive results is that you are optimistic about the power of the gospel to make personal and societal changes to the world. For the record, our church (RH3C) holds to the last view: premillennialism.
The last thing I will say is that - what is most crucial is not which view you believe in; it's whether or not you possess salvation in Christ. That's the most important thing: To repent of your sin and trust in Jesus. Whatever happens in the future, two things are for certain: Heaven is a glorious place free from sin, suffering and heartache. It is reserved for Christ-followers. Hell, on the other hand, is a place void of any good or beauty or love, because it is a place utterly removed of God's presence. It is reserved for those who do not have salvation.
I implore you to consider this heavily in your heart, and to receive God's salvation now, because your eternal destination depends on it. How we get there isn't so important. It's where we're going that is.
[Answered by Pastor HM]
References: Wayne Grudem, Systematic Theology (Nottingham: IVP, 1994), 1109ff.
