Believing is knowing. The thing is, that knowledge is purely personal, even if it is shared by other people. There is no way to judge beliefs. The only standard of truth for any belief is that a person happens to hold it: holding a belief makes it true for the people who hold it. Rejecting a belief does not make it false or wrong, either, except on an indivudals basis.

Recognizing the purely personal nature of all beliefs is what 'repsecting all religious beliefs' refers to. It must be added that all of that applies to secular/ideological beliefs every bit as much as it does to sacral/theological beliefs.