The problem is that seldom do you find agreement throughout a whole religion as theorists define religion. There isn’t really one Judaism, or one Christianity, or one Islam, or one Buddhism, or one Hinduism, or any other defined religion. No more than there’s one French language, or one Spanish, or one Italian, or one Mandarin, or one Cantonese. Religions have denominations and sects. Languages have dialects. Cultures have subcultures. And even the groups within each are influenced by those in the other overarching categories. We like to categorize and file everything because our minds, our Ruach, our Talker, likes order and organization. But life is messy and human interaction is messy. As black and white a thinker as I am, life is greys and colours. Life is Chaos and disorder. Order can only hold for so long before it falls apart, and the larger the area, the more people, it tries to control, the sooner and the faster it falls. Rome fell in Chaos because it got too big. The same is true over and over throughout history.
So it’s impossible to look at a religion only from what all it’s people believe, for there is no true Catholic (universally accepted) or Orthodox (the right belief). All dissolves into heterodoxy and heresy if you you look at it too closely. Chaos and Prophecy always overcome Order and Establishment. All is Paradox.
So how do you understand another religion? You have to look from within and from without. You have to look at tradition and the current state of it. And you have to understand that no statement can completely enclose the whole religion.