The Bible promises a seven-year period of Tribulation on Earth, but the final judgment moment for unbelievers waits for another 1,000 years. So why does God bother with bringing Tribulation on earth? What does it accomplish?
In Daniel 9, we learn three important details regarding the coming time of Tribulation. First, we learn that this period of time last one "week" (or literally "seven" in Hebrew). By the context of the historical events described in Daniel 9, it becomes clear that Daniel means a seven-year period of time.
Daniel says a total of seventy "sevens" (i.e., 490 years) have been decreed by God. Based on the timing of events Daniel provides in vs.25-26, we can see that 69 of of the 70 sevens have already transpired, leaving just one seven year period remaining. That remaining seven year period is the period of Tribulation, which has yet to happen.
Secondly, Daniel tells us God designated this period of 490 years for Daniel's "people." In other words, this is a period for Israel. Israel refers to the nation descended from Abraham and bound to the Old Covenant. By these terms, the Church is not "Daniel's people," so the Church is specifically excluded from the events of this 490 year period. This period began in 605 BC before the church was formed, and it was suspended when the Messiah was "cut off." Therefore, the church has never experienced any part of the 490-year period designated for Israel...nor will it ever!
Notice that all these purposes and outcomes are focused exclusively on preparing Israel to enter the Kingdom following Tribulation at Christ's Second Coming. This is further confirmation that this period of great distress on the Earth is focused entirely on Israel and not on the church. The extreme nature of the events during Tribulation impact the whole earth, but the intended target is Israel.
We find even more confirmation of this conclusion in Jeremiah's description of the Tribulation, when he labels it a "time of Jacob's (i.e., Israel's) distress:"
Ezek. 20:36 “As I entered into judgment with your fathers in the wilderness of the land of Egypt, so I will enter into judgment with you,” declares the Lord GOD.
Ezek. 20:38 and I will purge from you the rebels and those who transgress against Me; I will bring them out of the land where they sojourn, but they will not enter the land of Israel. Thus you will know that I am the LORD.
The Lord promises to bring Israel through a time of judgment and inspection (i.e., passing under the rod) so that He may purge Israel's sin and rebellion thereby bringing them back into the bond of the covenant. The covenant mentioned in this verse is the Old Covenant delivered through Moses.
You can read more about the nature and timing of the rapture of the Church in our Revelation study and by reading Explaining the Rapture.