There are a couple things that must be established to fully understand how he came to his conclusions. He takes the view that the gentile age began with the fall of Jerusalem in 587 BC to the Babylonian Empire. Remember this date. Luke 21:24 says that Jerusalem would be trodden down by the Gentiles, until the times of the Gentiles are fulfilled. From the Babylonians it passed to the Persians, Greeks, Romans, Byzantines, Arabs\Muslims, Crusaders, Mamluks, Ottoman Turks, British, and back to Israel. So, Jerusalem remained under gentile control from 587 BC until 1967 when Israel regained control of Jerusalem.

He holds that the number seven has prophetic significance, and can be found all throughout scripture. He uses this number in determining the length of the gentile age. He believes in all these prophecies a day represents a year. We can see several examples of this: a day is like a thousand years (2 Pe 3:8), the Hebrews wandered the desert 40 years, each for the number of days the spies were in Canaan (Num 14:34/Num 32:13), Ezekiel is told to lay on his left side 390 days, and his right side 40 days, the numbers representing years (Eze 4:4 – 4:8), and so on.

He uses three difference calendars. The 354 day lunar calendar, which is used by Jews and Muslims. The 360 day calendar (I've heard it also called the prophetic calendar), and the 365 day solar calendar (The Gregorian calendar we use). With this in mind, here is an excerpt where he ties it all together:

Thus we see the Gentile Age began with the fall of Jerusalem, B.C. 587. Now, if we know how long it is to continue, we can certainly ascertain proximately the time of the Lord’s coming. It is fanatical to appoint the day of His advent, which no one knows, from the simple fact that there are three distinct systems of chronology, all differing somewhat either from the other, and we do not know which chronology is correct, or whether any one of them is precisely right. In these expositions, it is pertinent that you keep all of the three chronologies — i.e., the lunar, calendar. and solar — constantly before your mind. Mohammedans and Jews use the lunar chronology, which contains three hundred and fifty-four days in the year; Europeans use the calendar, which contains three hundred and sixty days in the year; while Americans use the solar, which contains three hundred and sixty-five days in the year. How do we know the length of the Gentile Age? Leviticus 26: says several times over that the Jews shall suffer expatriation and persecution at the hands of the Gentiles seven times. Daniel 4:25, we find Nebuchadnezzar was crazy and exiled, playing king among the beasts of the field seven times. The Hebrew means seven years for Israel’s expatriation and Nebuchadnezzar’s insanity…

In all these prophecies, a day represents a year. Daniel predicted that it would be seventy weeks from the return of the Jews out of Babylonian captivity till Christ should come (Daniel 9:24). It is a well-known historic fact that this period proved to be four hundred and ninety years, thus, with many other prophecies, proving the year-day system of interpretation. The lunar year, 354 days, multiplied by 7, equals 2478; calendar, 360, multiplied by 7, equals 2520; and solar, 365, multiplied by 7, equals 2555. Hence. you see the time of Gentile rule in lunar chronology is 2478 in calendar, 2520; and in solar, 2555.

The period begins with the fall of Jerusalem, B.C. 587; now add A.D. 1896, and the total is 2483. So you see 2483 years have elapsed since the Gentile period began.

Now you will readily see when the Gentile Age will have an end. 2483 minus 2478 leaves 5. You see, according to lunar time, the Gentile Age has already expired, and five years over. 2520 minus 2483 leaves 37 years. Hence you see, according to calendar time, we have only thirty-seven years to await the Lord’s coming to reign. 2555 minus 2483 leaves 72 years. Here you see, according to solar chronology — the longest system — we have only seventy-two years to await the Lord’s kingdom.

To clarify what Godbey just said, he took each calendar year and multiplied it by seven. Here’s where it gets interesting. If we take those numbers and subtract it by 587 (the year Jerusalem fell) we get some interesting dates:

The 354-day lunar Calendar: (354 x 7) = 2478. (2478 – 587) = 1891. 1891 is the year Zionism was coined by Nathan Birnbaum to describe the new ideology of the Jews returning to their homeland. It was also the year the Blackstone Memorial was signed to petition U.S. president Benjamin Harrison to give then Palestine to the Jews.

The 360-day Calendar: (360 x 7) = 2520. (2520 – 587) = 1933. This was the year that Hitler came to power and was appointed Chancellor of Germany. This led to the Holocaust, and out of the Holocaust the nation of Israel was born in 1948.

The 365-day solar calendar: (365 x 7) = 2555. (2555 – 587) = 1968. This year marked the beginning of the reunification of Jerusalem with Israel. This date is a little tricky since as far as I know, we don’t know the exact day that Jerusalem fell. It is believed to have been in the summer month of Tammuz, which corresponds to June through July in the Gregorian calendar. If the fall of Jerusalem was before June 11th 587 BC then this date would fall on 1967, the year Israel captured Jerusalem during the Six-Day War. As Godbey said, it’s impossible to know if it is precisely right, so there’s a little room for error.

Godbey was incorrect that any of these dates would be the year that the Lord would return and reign, but he had remarkable insight for someone who lived in the 19th century and early part of the 20th century. When this book was written in 1896 he predicted the Ottoman Empire would fall, and he hoped Palestine would be turned over to the British Empire, who would then turn it over to the Jews, all of which happened.

If his calculations are correct, it only confirms what most of us here already believe. That the creation of Israel and the capture of Jerusalem was prophetic and ordained by God. It also means we truly are in the last of the last days. You may not agree with everything Godbey says, but if your interested you can read his commentaries for free. http://www.enterhisrest.org/history/wg-rev.pdf

p.s. Mods, I wasn’t sure which category to post this so feel free to move it if necessary. I don't necessarily want to debate it per say, but to discuss it. Thanks!