In terms of finances I think they're the biggest by a narrow margin, but they make up 15% of the membership (a huge chunk of which doesn't even participate), recently withdrew from both sponsoring the Varsity and Venturer programs, have all sorts of exceptions to the way they run the program that no one else does, and a majority supports withdrawing entirely, but sure - let's blame Mormons for a stance the organization had before they even partnered up.