Day of Christ

From Anstey’s Doctrinal Definitions:

This term refers to the time when Christ will be displayed with the Church in manifested glory before the world (2 Thess. 1:1010When he shall come to be glorified in his saints, and to be admired in all them that believe (because our testimony among you was believed) in that day. (2 Thessalonians 1:10); John 17:2323I in them, and thou in me, that they may be made perfect in one; and that the world may know that thou hast sent me, and hast loved them, as thou hast loved me. (John 17:23)). The “day of Christ” (or “the day of Jesus Christ”) will begin at the Appearing of Christ and will continue throughout the Millennium (1 Cor. 1:8; 3:13; 5:58Who shall also confirm you unto the end, that ye may be blameless in the day of our Lord Jesus Christ. (1 Corinthians 1:8)
13Every man's work shall be made manifest: for the day shall declare it, because it shall be revealed by fire; and the fire shall try every man's work of what sort it is. (1 Corinthians 3:13)
5To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus. (1 Corinthians 5:5); 2 Cor. 1:1414As also ye have acknowledged us in part, that we are your rejoicing, even as ye also are ours in the day of the Lord Jesus. (2 Corinthians 1:14); Phil. 1:6, 10; 2:166Being confident of this very thing, that he which hath begun a good work in you will perform it until the day of Jesus Christ: (Philippians 1:6)
10That ye may approve things that are excellent; that ye may be sincere and without offence till the day of Christ; (Philippians 1:10)
16Holding forth the word of life; that I may rejoice in the day of Christ, that I have not run in vain, neither labored in vain. (Philippians 2:16)). Thus, it will last 1000 years. The day of Christ is abbreviated to “that day” in some places in Paul’s epistles (2 Thess. 1:1010When he shall come to be glorified in his saints, and to be admired in all them that believe (because our testimony among you was believed) in that day. (2 Thessalonians 1:10); 2 Tim. 1:12, 18; 4:812For the which cause I also suffer these things: nevertheless I am not ashamed: for I know whom I have believed, and am persuaded that he is able to keep that which I have committed unto him against that day. (2 Timothy 1:12)
18The Lord grant unto him that he may find mercy of the Lord in that day: and in how many things he ministered unto me at Ephesus, thou knowest very well. (2 Timothy 1:18)
8Henceforth there is laid up for me a crown of righteousness, which the Lord, the righteous judge, shall give me at that day: and not to me only, but unto all them also that love his appearing. (2 Timothy 4:8)). The rewards which the saints will receive at the judgment seat of Christ will be on display then (1 Cor. 3:1313Every man's work shall be made manifest: for the day shall declare it, because it shall be revealed by fire; and the fire shall try every man's work of what sort it is. (1 Corinthians 3:13); 2 Tim. 1:1212For the which cause I also suffer these things: nevertheless I am not ashamed: for I know whom I have believed, and am persuaded that he is able to keep that which I have committed unto him against that day. (2 Timothy 1:12); Phil. 2:1616Holding forth the word of life; that I may rejoice in the day of Christ, that I have not run in vain, neither labored in vain. (Philippians 2:16)).
“The day of Christ” is not the day that the Lord spoke of in the upper room when He said, “In that day....” (John 14:20; 16: 23, 2620At that day ye shall know that I am in my Father, and ye in me, and I in you. (John 14:20)). The Lord was speaking of this present day when the Spirit would come to reside on earth in the Church. Nor is it the same day that the Old Testament prophets spoke of when they said, “In that day....” (Zech. 12:3, 4, 6, 8, 9, 11; 13:1, 2, 43And in that day will I make Jerusalem a burdensome stone for all people: all that burden themselves with it shall be cut in pieces, though all the people of the earth be gathered together against it. 4In that day, saith the Lord, I will smite every horse with astonishment, and his rider with madness: and I will open mine eyes upon the house of Judah, and will smite every horse of the people with blindness. (Zechariah 12:3‑4)
6In that day will I make the governors of Judah like an hearth of fire among the wood, and like a torch of fire in a sheaf; and they shall devour all the people round about, on the right hand and on the left: and Jerusalem shall be inhabited again in her own place, even in Jerusalem. (Zechariah 12:6)
8In that day shall the Lord defend the inhabitants of Jerusalem; and he that is feeble among them at that day shall be as David; and the house of David shall be as God, as the angel of the Lord before them. 9And it shall come to pass in that day, that I will seek to destroy all the nations that come against Jerusalem. (Zechariah 12:8‑9)
11In that day shall there be a great mourning in Jerusalem, as the mourning of Hadadrimmon in the valley of Megiddon. (Zechariah 12:11)
1In that day there shall be a fountain opened to the house of David and to the inhabitants of Jerusalem for sin and for uncleanness. 2And it shall come to pass in that day, saith the Lord of hosts, that I will cut off the names of the idols out of the land, and they shall no more be remembered: and also I will cause the prophets and the unclean spirit to pass out of the land. (Zechariah 13:1‑2)
4And it shall come to pass in that day, that the prophets shall be ashamed every one of his vision, when he hath prophesied; neither shall they wear a rough garment to deceive: (Zechariah 13:4), etc.) which is the Messiah’s day on earth in connection with Israel. The day of Christ has to do with His heavenly glory with the Church.
“The day of Christ” and “the day of the Lord” refer to the same period of time (the Millennium); the former emphasizes the display of Christ’s glory and the latter the exercise of His judgment.