A time when those who are dead in Christ (those in Paradise), will have their spirits and their bodies reunited and the second death will have no power over them. During this time those who are righteous will be the only ones on the earth. Because they have rejected Satan, and chosen God and His ways, Satan will have no power to operate. Satan will be bound for a thousand years. (Rev. 20: 1-3)
In I Peter 3:18-20 we are told that Jesus preached to the Spirits in prison. This implies that those spirits in prison (Hell) had the ability to learn and change. We can also apply this to those in the First resurrection, that they will continue to learn and have the same opportunity to be judged as men and women in the flesh. If we are in the process of doing our very best at death we will continue to grow in this one thousand years toward complete perfection.
(John 5:28 KJV) Marvel not at this: for the hour is coming, in the which all that are in the graves shall hear his voice, and shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation.
(Acts 2:31 KJV) He seeing this before spake of the resurrection of Christ, that his soul was not left in hell, neither his flesh did see corruption.
(Acts 24:15 KJV) And have hope toward God, which they themselves also allow, that there shall be a resurrection of the dead, both of the just and unjust.
(1 Th 4:14 KJV) For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him.
(Rev 20:6 KJV) Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.