You don't create a core ideology, you discover it. Ideology has to be authentic. Also be clear that the role of core ideology is to guide and inspire, not to differentiate.  Thereby, core ideology needs to be meaningfuland inspirational only to people inside the organization, because it is the people inside the organization who need to commit to the organizational ideology over the long term. You can't impose new core values or purpose on people. A company can have a strong core ideology without a formal statement. In writing down the core ideology you should focus on getting the content right, on capturing the essence of the core values and purpose.