Of course beliefs can change, as long as each person gets to a point, where they can no longer reconcile their previous belief any longer and they move on.
I was a Christian for 40 years, so I changed my belief and did so because I acquired new knowledge as time went on, and I could no longer reconcile my belief as being legitimate. Changes like this don't happen overnight, but are typically a slow burn of recognizing a prior belief to be wrong and also when that person is willing to give up the previous belief, from a psychological standpoint. This process happens in a complex way and much of it is not by choice and not a conscious choice.
People with strong beliefs when faced with evidence their belief may be wrong will not immediately accept they are wrong, but will utilize defense mechanisms to protect the belief; denial, confirmation bias etc.. Why? Because when it is too painful to admit your belief may be wrong, your psyche will work to protect it, to ward of this discomfort. With some (as with me) the evidence became so overwhelming that my belief was wrong, it would have been more painful to pretend I could ignore this new knowledge and play mind games with myself and it was less painful to give up the belief and acknowledge well evidenced reality.