Between this life and eternity is the intermediate state. Because this is an "in-between" state there is a certain amount of incompleteness. All of the promises of God are not experienced in the intermediate state. The intermediate state is incomplete for the believer in at least three ways.
1. The Body Of Christ, The Church, Remains Incomplete
The church, or the body of Christ, is presently incomplete. This will be the case until the last person enters into the body of Christ by believing in Jesus as their Savior. The writer to the Hebrews noted.
God had planned something better for us so that only together with us would they be made perfect (Hebrews 11:40).
At that time, when all the believers are together, the intermediate state will end. Believers will raised in their new bodies, receive their rewards, and then Christ will return.
2. Believers Do Not Have Glorified Body
The intermediate state of the believer is incomplete in the sense that their body has not been glorified. Whether the believer remains disembodied, or has some sort of temporary body in the intermediate state, the final glorified body has not yet been given.
3. They Are Limited To Heaven
Those in the intermediate state are limited to heaven. However, the earth also belongs to those who have believed in God's promises. The Lord has promised that He will put His kingdom upon the earth. Yet the earth is still in a state of sin, awaiting the time when Christ returns and deals with the sin problem.
Not Total Contrast
The intermediate state, however, does have much in common with the final state - there is not a total contrast between the two. It is basically a transitional place from the earthly existence to the heavenly with many of the benefits of heaven.
Straight To Final Resting Place?
There are some who deny that any intermediate state exists for the believer or unbeliever. This view holds that the spirits of the dead go to their final resting place upon death. When Scripture speaks of judgment and resurrection, they believe that it is only figurative. They say that each individual is judged at death. For this particular viewpoint, death and resurrection would then be identical.
Response
This view has to spiritualize the plain teaching of the Scripture on the subject, as well as reinterpret the events around Second Coming of Christ. There is no warrant for understanding what the Bible has to say about the death, resurrection, and the coming of Christ in anything but a literal manner.
Necessary
The fact that there will be a resurrection and then an ultimate judgment, makes some type of "in-between" or "intermediate state necessary. After each person dies, they await the final judgment of God.
Summary
The intermediate state, though much greater for the believer than the present earthly existence, is still incomplete for the following reasons.
1. They are still awaiting for the church, the body of Christ, to be complete.
2. Their own glorified body is not received until the resurrection.
3. They only have access to heaven, not to earth.