Belief means holding something to be true in philosophy

[Ben Davis]

There are some on this forum who use the term belief to imply doubt but contemporary analytic philosophers of mind generally use the term “belief” to refer to the attitude we have, roughly, whenever we take something to be the case or regard it as true.

Nope. You're misunderstanding the contemporary view the 'knowledge' is a subset of 'belief' commonly called 'justified-true belief'. This is a response to Descartes and allows philosophers to separate perceptual reality from the existential doubts (when agreed in definitions).

Consequently everything else you wrote is wrong.

Lots of people claim not to have belief in what they know - can we drop this more sloppy usage in the forum.

Well, I won't because it's not sloppy, it's granular and precise when applied to preceptual reality and justified-true belief. You just misunderstand its use.