Try this experiment. Type the expression in quotes “I know the church is true” into a Google search, and see what you get. Page after page after page of material set in a Mormon context. That kind of affirmation is a specifically Mormon thing; it is not something other Christians are in the habit of saying about their churches. If you can go through an entire Fast and Testimony Meeting and not get at least a dozen recitations of that statement, it has been a slow Sunday.
I have noticed over the last several decades that, increasingly, expressions of faith are no longer perceived as good enough. Only expressions of KNOWLEDGE!, with its greater perceived certainty, are considered the normative form of discourse in a F&T meeting.