The primary objection advanced against Bible codes of the Drosnin variety is that information theory does not prohibit noise from appearing to be sometimes meaningful. Thus, similar patterns can be found in books other than the Bible. Although the probability of an ELS in a random place being a meaningful word is small, there are so many possible starting points and skip patterns that many such words are completely expected to appear.

Responding to an explicit challenge from Drosnin, who claimed that other texts such as Moby Dick could not yield ELS, Australian mathematician Brendan McKay found many ELS letter arrays in Moby Dick that relate to modern events, including the assassination of Martin Luther King, Jr. He also found a code relating to the Rabin assassination, containing the assassin's first and last name and the university he attended, as well as the motive ("Oslo", relating to the Oslo accords.) [2]

Other people, such as US physicist Dave Thomas, found other examples in many texts. In addition, Drosnin had used the flexibility of Hebrew orthography to his advantage, freely mixing classic (no vowels, Y and W strictly consonant) and modern (Y and W used to indicate i and u vowels) modes, as well as variances in spelling of K and T, to wrench out the desired meaning. In his television series John Safran vs God, Australian television personality John Safran worked successfully with McKay to look for evidence of the September 11 terrorist attacks on New York in the lyrics of Vanilla Ice's repertoire. Additionally, the known coded references in Bible texts, as for instance the famous Number of the Beast, do not use the Bible code technique. And, the influence and consequences of scribal errors (eg, misspellings, additions, deletions, misreadings, ...) are hard to account for in the context of a Bible coded message left secretly in the text.

Code proponents respond by claiming that the ELS letter arrays appearing in the Bible are better in some way than those appearing in other books. They also investigate alternative types of codes and cyphers to stay ahead of criticism. However, in the absence of an objective measure of quality, and an objective way to select test subjects, it is not possible to positively determine whether any particular observation is significant or not. For that reason, most of the serious effort of the skeptics has been focused on the "scientific" claims of Witztum, Rips and Gans.

In 1999, McKay, together with mathematicians Dror Bar-Natan and Gil Kalai, and psychologist Maya Bar-Hillel, published a paper in Statistical Science which they claim provides an adequate refutation of the earlier paper of Witztum and Rips. The paper was reviewed anonomously by four professional Statisticians who found their refutation completely conclusive.

Their main points were:

The data used by Witztum and Rips was a list of rabbi names in Hebrew. The Hebrew language is somewhat flexible as far as name spelling goes, and each rabbi has several different appellations (aliases and nicknames), so special care should be taken as to how to choose the particular names searched for. So their result could be explained by claiming the data was not collected properly. From the paper: "...the data was very far from [being] tightly defined by the rules of their experiment. Rather, there was enormous "wiggle room" available, especially in the choice of names for the famous rabbis".
There is indirect evidence that the data was not, in fact, collected properly; that is, the choice of names and spellings was somehow biased towards those supporting the codes hypothesis.
Attempts at replicating the experiment failed to achieve the same result. From the paper: "A technical problem that gave us some difficulty is that WRR have been unable to provide us with their original computer programs. Neither the two programs distributed by WRR, nor our own independent implementations of the algorithm as described in WRR's papers, consistently produce the exact distances listed [by WRR]".
The McKay paper did not go so far as to accuse Witzum and Rips of falsifying their experiment, instead it argues that the ELS experiment is extraordinarily sensitive to very small changes in the spellings of appellations. This fact, when combined with available wiggle room, was exploited by McKay et al. to duplicate the Genesis result in a Hebrew translation of War and Peace.

There has been a continuing debate on these claims. (See the web pages cited below.)

The experiment of Gans has also received critical attention. Several attempts at replicating it, designed by mathematician Barry Simon, gave negative results. Finally, a committee at the Hebrew University, comprising both code proponents and skeptics, ran two replications using outside experts to compile the data. Both replications failed to find the phenomenon that Gans' original experiment claimed to find.

As of 2003, there are still a few university scientists who see evidence for such hidden messages. The most notable are Eliyahu Rips (see above) and Robert Haralick (an electrical engineer at the City University of New York). However, the overwhelming majority of scientists who have investigated these claims reject them.

ELSs are very sensitive to single-letter insertions. Jeffrey Tigay attacks the notion that there exists a single text in which to search for ELSs by pointing out the long history of scholarship on textual variations in the Hebrew Bible text. The significance of ELSs would seem to diminish in the face of hundreds or perhaps thousands of spelling drifts (often taking the form of letter insertions) in the text over time. There are similar variant readings and scribal distortions in the New Testament.

- wikipedia.org