Epistemology is the study of the nature and conditions of knowledge. Western philosophy since Plato (or Socrates -- not sure we'll ever know which) has, by and large, offered a classic epistemic package that may be summed up thusly:
Belief that is True and Justified is Knowledge. K = JTB.
On this understanding, when people claim to have not beliefs but knowledge, they are confused. They have beliefs, and are attempting to bypass the asked-for account that presents a rational account for the probability that their beliefs are both True and Justified. They're either unconscious of what they are doing or they are intellectual cheats if they simply assert there knowledge against your belief. Putting adjectives in front of them, like say scientific knowledge versus religious belief, only dresses up the attempted epistemic crime. While you may be practically justified in having a belief you can't give an adequate justificatory account for, when arguing, account for the claim or shut up. Don't just assert with more force.
The classic epistemic package: may it live another few thousand years at least, triumphing over postmodern, politically-dominated, and post-colonial BS excuses for epistemology -- and over Gettier-type objections. Hears to hoping we all grow in knowledge.