“Probation” is a word that does not appear in the Book of Revelation (or anywhere else in the Bible). The legal meaning (a period of time in which someone who has broken the law has to “be good” in order to avoid the punishment he has been sentenced to) does not really describe what God does, but since there is some similarity the term has been used.
The concept is that nations and individuals are given a “probationary” period of time in which they must meet God’s requirements. For example, in Daniel 9 the nation of Judah was given a probationary period of 490 years (“seventy weeks”) to “finish the transgression, to make an end of sins, to make reconciliation for iniquity, to bring in everlasting righteousness, to seal up vision and prophecy and to anoint the Most Holy” (Daniel 9:24).
This period would extend “from the going forth of the command to restore and build Jerusalem until Messiah the Prince (Jesus Christ)” (v. 25). They failed to meet the requirements, so at the “end of their probation” Jesus announced, “The kingdom of God will be taken from you and given to a nation bearing the fruits of it” (Matthew 21:43).
Each person’s probationary period ends when he dies; until that time he can believe, repent and be forgiven through the blood of Jesus, and he will be granted eternal life. But if he does not believe and repent by the time he dies he will suffer eternal death. There is no second chance after probation closes (“It is appointed for men to die once, and after this the judgment”, Hebrews 9:27).
However, there is a special case for those who are alive at the Second Coming of Christ. They will have already been judged, because when Jesus comes “His reward is with Him” (Isaiah 62:11). The “righteous” will “be caught up together with (the dead in Christ) to meet the Lord in the air” (1 Thessalonians 4:17). The “wicked”, on the other hand, will be killed when Jesus comes and will be eaten by the birds (Revelation 19:21).
Obviously they have already been judged, which means that at some point prior to the Second Coming the judgment of everyone will be completed— this is what is called the “Close of Probation”. This is taught in a number of the parables of Christ, such as the parable of the ten virgins: five of the virgins were not ready for “the bridegroom” (Jesus). “Those who were ready went in with him to the wedding; and the door was shut. Afterward the other virgins came also, saying, ‘Lord Lord, open to us!’ But he answered and said, Assuredly I say to you, I do not know you” (Matthew 25:10-12).
The close of probation is expressed in Revelation with the solemn declaration, “He who is unjust, let him be unjust still; he who is filthy, let him be filthy still; he who is righteous, let him be righteous still; he who is holy, let him be holy still. And behold I am coming quickly, and My reward is with Me, to give to every one according to his work” (Revelation 22:11,12).
Christ’s mediation for us is symbolized in Revelation by “the temple of the tabernacle of the testimony in heaven”, which is “open” allowing us access to Jesus (Revelation 11:19, 15:5). The close of probation is described in Revelation 15:8: “The temple was filled with smoke from the glory of God and from His power, and no one was able to enter the temple”. This takes place after the Seven Trumpets and before the Seven Last Plagues.
Events in Revelation that take place before the Close of Probation include the Investigative Judgment, the sealing of the 144,000, the war described in the Seven Trumpets, the ministry of the Two Witnesses, the appearance of the Beast from the bottomless pit, the Mark and Number of the Beast, the Three Angels’ Messages and the Great Multitude coming out of Babylon.
Events that take place after the Close of Probation include the Seven Last Plagues, the destruction of Babylon, the Battle of Armageddon, the Second Coming of Christ, the Millennium, the White Throne judgment and the establishment of the New Jerusalem on earth.
For more information see section 15:5-8 The Close of Probation in The Book.