Mystery can be seductive. If we are not careful it can lead us into god-of-the-gaps thinking. We can be lulled into thinking that because something is so lacking in explanation we can explain it away as miraculous. This is bad science, bad theology and bad philosophy. Mystery can point to common sense. And mystery can establish criteria.
There are scientific mysteries, many of them. The outstanding mystery is how the images are formed. As Philip Ball, a former physical sciences editor for for Nature, that most prestigious international science journal, the same journal that had published the carbon dating results in 1989. wrote in Nature Online: "It is simply not known how the ghostly image of a serene, bearded man was made." That was true when he wrote that in January of 2005 and it is still true. But this has led some to opine that the answer is beyond science. It may be. But there is no way to know and it is completely possible that someone will figure it out. This has also led to some ridiculous attempts to show how the image might have been created by a forger. So far, no one has been able to do so, despite what you might sometimes read in the press.
There are historical mysteries. That is not uncommon with medieval and earlier history. Historical records confuse dates, leave out facts and often contain mixtures of historical events, myth and legends. It is the job of the objective historian to sort all this out. Gaps in records have led to some profoundly poor historical statements. None is perhaps more incorrect that the statement that there is no history of the Shroud before the 1350s. The correct statement is there appear to be no Western-European written records for the Shroud before the 1350s. In looking at the historical conspectus from Byzantium, we can conclude that there seems to be a gap in the record. Gaps in ancient records are common. But even that record is closing.
Mystery is never evidence. We should take mystery seriously. Perhaps some answers can only be found through belief in God. But we must remember that we are using the word belief. When it comes to methodical science and disciplined historical assessment, we must remember that mystery always means unanswered questions that we should seek to answer.