Yes, the millennial reign of Christ occurs after tribulation. The Lord Jesus Himself taught this in Matthew 24:29-30 and 25:31, “Immediately AFTER THE TRIBULATION of those days the sun will be darkened, and the moon will not give its light; the stars will fall from heaven, and the powers of the heavens will be shaken. THEN the sign of the Son of man will appear in heaven, and THEN all the tribes of the earth will mourn, and they will see the Son of Man coming on the clouds of heaven with power and great glory….When the Son of Man comes in His glory, and all the holy angels with Him. THEN He will sit on the throne of His glory” (NKJV). In addition to the Lord sitting on His throne to reign over the earth, the Apostle John wrote: “And I saw thrones, and they sat on them, and judgment was committed to them. Then I saw the souls of those who had been beheaded for their witness to Jesus and for the word of God, who had not worshiped the beast or his image, and had not received his mark on their foreheads or on their hands. And THEY LIVED AND REIGNED WITH CHRIST FOR A THOUSAND YEARS” (Revelation 20:4-5.) So, not only will Christ “sit on His throne” to reign for 1,000 years, but all who had died believing in Christ (during Old Testament days, during the Church Age, and during the Tribulation Period) will also “sit on thrones” and will reign “with Christ for a thousand years.”

Regarding your question about unbelievers, I believe they will all be judged BEFORE the 1,000 year kingdom begins. Of course, many unbelievers will die during the Tribulation judgments outlined in Revelation chapters 6-18. Then there will be untold numbers who are killed when the Lord appears. We read of this in Revelation 19:11, 15, 17-21: “Now I saw the heaven opened, and behold, a white horse. And He who sat on him was called Faithful and True, and in righteousness He judges and make war…Now out of His mouth goes a sharp sword, that with it He should strike the nations…Then I saw an angel…and he cried with a loud voice, saying to all the birds that fly in the midst of heaven, ‘Come and gather together for the supper of the great God, that you may eat the flesh of kings, the flesh of captains, the flesh of mighty men….and the flesh of all people, free and slave, both small and great…And the rest of the dead were killed with the sword which proceeded from the mouth of Him who sat on the horse. And all the birds were filled with their flesh.”  I believe this takes place in Israel, at a place called “Armageddon,” where armies around the world will assemble for battle (see Revelation 16:12-16). The Lord Jesus will also judge other “rebel armies” (in Israel) at “the Valley of Jehoshaphat” (see Joel 3:1-2, 11-16; Zechariah 14:1-4, 12-13; and Daniel 8:23-25; 11:40-45).

After the Lord deals with all the rebellious armies of the world that rebel against Him, He will then JUDGE ALL THE LIVING to determine whether or not they will enter His 1,000 kingdom on earth or enter into everlasting fire. We had already quoted Matthew 25:31 which showed us the coming of Christ in power and glory. Now we will read verses 32-34 and 41, “All the nations will be gathered before Him, and He will separate them one from another, as a shepherd divides his sheep for the goats. And He will see the sheep on His right hand, but the goats on the left. Then the King will say to those on His right hand, ‘Come, you blessed of My Father, inherit the kingdom prepared for you from the foundation of the world’….Then He will say also to those on the left hand, ‘Depart from Me, you curse, into the everlasting fire prepared for the devil and his angels.’” Of course, the “sheep” represent “believers” and the “goats” represent “unbelievers.” All living believers, who survived the Tribulation, will enter into the kingdom here on earth. All living unbelievers, who survived the Tribulation and were not present at the battle of Armageddon, will enter into everlasting fire. Thus we learn in the passages quoted today that ALL UNBELIEVERS WILL BE JUDGED prior to the 1,000 kingdom; some will actually be killed by the Lord Jesus (the “Warrior King and Judge”) at Armageddon or the Valley of Jehoshaphat, and others will be cast into the lake of fire.  (445.3)  (DO)