danlowlite has offered an instance of what happens when unsupported claims and unverified discoveries are taken as canon.

He is refering to a supposedly lost epistle of Clement of Alexandria, claimed to be discovered by Dr. Morton Smith, hand-written on the back page and inside cover of a 17th Century edition of The Epistles of Ignatius of Antioch in the library of the Mar Saba monestary. The epistle reportedly contained segments of Mark's gospel which were repressed by the Church.

The discovery was supposedly made in 1958. It was first mentioned in public at a meeting of the International Bible Society in 1960, although the text was not released for scholarly review until 1973 (along with Smith's notes and translation). Noone but Smith has ever seen the text which he claims to have discovered. Apparently the relevant pages of the printed volume on which it was found were "removed for repair" and they were never seen or heard from again.

This story has all the plot devices of a great conspiracy theory; if one is paranoid enough, it becomes circularly self-evident and unfalsifiable.

"See! The Church is STILL repressing the text!"

The problems with taking the the text as (cough, cough) gospel are numerous; some obvious, some less so.

So, in short, we have:

  1. A manuscript that many doubt even existed;
  2. If it does/did exist, many doubt that it was written by Clement;
  3. If it does/did exist and it was written by Clement, most don't take Clement as a reliable source about the data;
  4. If it does/did exist and it was written by Clement, the passage dealing with Jesus seems to be constructed from the original gospels (like the gnostic documents of the 2nd century)

Thanks to http://www.christian-thinktank.com/qbadmark.htmlfor helping structure this argument.