Scientific knowledge versus spiritual knowledge

[robvalue]

The problem with knowledge being a true belief is that no one can ever be certain that anything is true. So what is actually knowledge, out of our "knowledge" is unknown and unknowable I would say. Also, if it is true, justification is irrelevant.

It is a tricky word to define, for sure. Informally, I'd just say knowledge on a personal level is justified belief. The knowledge pool however represents beliefs that have stood up to a reasonable amount of scrutiny from everyone and still appear to be most likely true. So again it is justified belief, with the justification being much more rigorous.

These are just my definitions.

For me, something falls out of the knowledge category when you are unable to justify it to anyone but yourself.  Like you said, if something can hold up to a reasonable amount of scrutiny by many others we can be at least more certain (if never 100% certain) that it is true.  The dictionary definition of knowledge includes knowledge by way of personal experience, but not by pure experience alone.  

It is my experience that when I give extra protein to patients with bed sores, they get better.  Though this IS a personal experience, I can also demonstrate it to the rest of the medical team, to the patient, to the patient's family, and I can reproduce those results over and over again.  If I just claimed to have knowledge of how to heal bed sores, by casting an anti-bed sore spell, but none ever actually healed, then I don't actually have any knowledge about how to heal bed sores.  It's not justified.  Even if I really, really, believe that I KNOW, at the end of the day I have no way of demonstrating it.  

Sometimes I have beliefs, but I can't justify them to myself. It's in those situations where I seek evidence to convince myself, or else accept it is nothing but intuition or a hunch and not to put too much stock in it.

I think the difference between a sceptic and a non-sceptic is the ability to assess one's own beliefs and methods of collecting "evidence" as objectively as possible. In other words, the sceptic is very aware that they are fallible and seeks to minimise errors this can cause.