Creeds are usually an established set of religious beliefs and rules for one to follow or obey. They determine how people should act and establishes faith. Christians have many creeds they are supposed to obey. An example would be the Creed of Hippolytus.
An interrogatory creed is one that asks a question. An example would be "Do you believe in God the Father Almighty?"
A declaritive creed would be a creed that would be given in the form of a statement. It does not ask a question but simply tells you what to do or how to behave, etc. It sets the groundwork for faith.
Marthaler discussed creeds from the Roman Catholic Church. He takes creeds, or beliefs, and puts them into an easy to understand contemporary form.