Oh, and by the way, the article is hitting on the of the actual big issues in philosophy, commonly called the problem of the criterion (So named by Roderick Chisholm).
When we are trying to determine how to know anything, we can start one of two ways (Here I'm mostly copying fom Wikipedia due to laziness):
1. What do we know? or What is the extent of our knowledge?
2. How do we know? or What is the criterion of knowing?
An answer to either set of questions will allow us to devise a means of answering the other. A skeptic will proclaim that since one cannot have an answer to the first set of questions without first answering the second set, and one cannot hope to answer the second set of questions without first knowing the answers to the first set, we are, therefore, unable to answer either.
So, in order to know anything we have to engage in circular reasoning, or so the problem seems. Not to say this is unsurmountable, but this question is giving philosophers a big headache. So presuppositions lists just pick "The Bible" as an answer to question 1 in order to start somewhere.