Four: the answer posed by the question from the name of the forum.

Four is the number of letters of the name of "G-d": the Tetragrammaton ( see: http://en.wikipedia.org/wiki/Tetragrammaton ). It is interesting to note that "the Dead Sea Scrolls and other Hebrew and Aramaic texts write ( only ) the Tetragrammaton in paleo-Hebrew, showing that the name was treated specially. "

It's quite common to see precisely four objects/concepts in a category/class in the world, often with one of these being particularly interesting or unique ( or in some sense, quite unlike the others ) and often these all point to something beyond and in reality, ultimately to Hashem ~ "G-d".

Four-word bible
------------------

This post was really prompted by the Ruach HaKodesh ~ Spirit of Truth, especially after reading about the "four-word bible" within the last day. IMHO, one of the best versions of the four-word four-letter bible would look pretty close to:

YHWH - Torah - Yeshua - Ahava

( Note that each of the above words written in Hebrew have precisely four letters ).

YHWH is simply the Tetragrammaton or the name of "G-d".
Torah could mean instruction or more concretely refers to the Pentateuch.
Yeshua is the name of the Messiah, often referred to by Christians as "Jesus".
Ahava is the Hebrew word for love, which means more like sacrificial giving, or is close to "agape" love which is generally considered as unconditional and voluntary.

-------

This leads to questions I would like to direct especially to the theists:

What instances of "four" in the world do you see, in your opinion, point to "G-d" ?

and

What instances of "four" in the world do you see, in your opinion, point to "something beyond" ?

Here's an interesting talk by Michael Atiyah ( Fields Medalist, Abel Prize winner, etc. ) suggesting that there are four fundamental forces of nature precisely because there are exactly four division algebras [ in the 19th century, both Frobenius and Peirce proved that there were only three associative division algebras; the Cayley algebra is the only nonassociative division algebra ]:

https://www.youtube.com/watch?v=I1ftUA17MZg


Of course, he's in the Dirac camp of the beauty of a theory which goes far beyond the Wignerian idea of the effectiveness of mathematics in physics.

The Islamic tradition typically has much more emphasis on numerology and have had on several occasions, upon finding out that I am a mathematician, Muslims going on and on about the mathematical miracles of the Koran. It stems at least in part from the fact that the Koran is more fixed in its exact word for word copies than the bible is, which lends itself to such numerological arguments where you count words in a surah.

Based in this experience, I would highly recommend not trying such an approach.

But four=twoplustwo!

19 is a significant number in Islam, but the name of "G-d" is expressed by four Hebrew letters.

Four dimensional spaces have been found to be quite unique in the last few decades, a remarkable "prophecy" suggested by Dirac.