Original: Problems with Q A principal objection to the 2SH is that it requires a hypothetical document, Q, the existence of which is not attested in any way, either by existing fragments (and a great many fragments of early Christian documents do exist) or by early Church tradition.
Simplified: The two source hypothesis requires a second source, called Q. The problem is that this source is not mentioned in the many fragments of early Christian texts that were found, or in the early Christian Church tradition.