English Other Religion

First paragraph:
"The Bible ties together the flood of Noahs day and May 21, 2011 which came exactly 7000 years later (4990 BC + 2011 = 7001 – 1 = 7000) . Since May 21, 2011 was the last day of the Great Tribulation period and also fell 7000 years precisely from the date of the flood, and since it also had the underlying Hebrew calendar date of the 17th day of the 2nd month (which matched precisely with the day that God shut the door of the ark and brought the flood to devastate the world), we can be sure that God placed His hand on May 21, 2011, as the day that the door of heaven was shut to the unsaved inhabitants of the earth."

Second paragraph:
"For example, from the flood to May 21, 2011 was exactly 7,000 years to the equivalent selfsame day, with the underlying Hebrew calendar date."


I didn't bother translating it in the first paragraph because it seemed unnecessary, but now I'm not sure how to best interpret this word (underlying). Do you think it would mean something like "implied" or "basic"? Thank you.

PS: The two paragraphs are from a text of a transcribed speech, and it includes lots of incoherent statements because it was apparently made spontaneously or near-spontaneously.