Here is a short syllogism that has to premises that SEEM true, but which lead to a conclusion that utterly undermines the very scriptures they seek to bolster.
Premise 1) SCRIPTURE IS THE SOLE/ONLY INFALLBILE SOURCE OF AUTHORITY
Premise 2) THE CANON OF SCRIPTURE IS NOT IN SCRIPTURE.
CONCLUSION: THEREFORE, THE CANON OF SCRIPTURE IS FALLIBLE
One of those