This leads to problems like the following:
(1) If such people knew/know that 2+4+2=8, then according to the Qur’an it would be/is a lie, which is absurd. (This might help Muhammad and his followers out of a bind (q.v. Surah 41:9-12), but it would lead to an untold number of other problems.)
(2) If it is true that such people knew/know only lies, then they wouldn't have known/know that they existed/exist. If they did/do know that they existed/exist, then it would have been/is a “lie”, but if their existence was/is a lie, then how did/do they know it since non-existent persons can’t know anything?
(3) It is not possible to “know” only lies, for in the nature of the case a lie can be believed but it cannot be known.
These problems don’t go away even if one tries to restrict the lies “known” by Scriptural illiterates to that which regards “the book”, for once again, it is not possible to know any lies, whether they are about the book or something other than the book. Lies cannot be known. Period. The tenacity of this point also doesn’t go away if one resorts to other translations, for they all yield a similar set of problems.
****Many thanks to PM for alerting me to this****