"Your father Abraham rejoiced to see my day: and he saw it, and was glad." (John 8:56)
Jesus spoke to the Pharisees about "my day"--a day which Abraham had "seen" 2,000 years before. This evidently referred to the time when Christ would be on earth, which God had enabled Abraham to see in prophecy.
But of all the days when He was on the earth, the most glorious was the great day when He rose from the dead. "He hath raised up Jesus again; as it is also written in the second psalm, Thou art my Son, this day have I begotten thee" (Acts 13:33).
As a result of His death and resurrection, "behold, now is the day of salvation" (2 Corinthians 6:2). The day of salvation is any day in this age of grace when a person believes on Christ for salvation. He then receives "the holy Spirit of God, whereby ye are sealed unto the day of redemption" (Ephesians 4:30). This great future day of redemption evidently is the same as "the day of Jesus Christ" (Philippians 1:6), when He comes again.
Following this is the fearful day of the Lord, when Christ will punish and judge and reign. "The day of the Lord so cometh as a thief in the night . . . and they shall not escape" (1 Thessalonians 5:2-3). It is also called "the great day of his wrath" (Revelation 6:17).
This day of the Lord will culminate at God's great white throne. This will be "the day of wrath and revelation of the righteous judgment of God" (Romans 2:5).
Finally will come the eternal "day of God" when this present earth will be purified with fire and "we, according to his promise, look for new heavens and a new earth, wherein dwelleth righteousness" (2 Peter 3:13). That day will never end, "for there shall be no night there" (Revelation 21:25). HMM