"They had to sacrifice animals..." Had to!...what was accomplished by animal sacrifice, except that it replaced human? What concept of the Creator of All does one have to have to think that Creator somehow was aggrandized by such a practice?
It is things like this that make such discussions a dead end. The fact is, the nature of what 'God' would be is so beyond human capacity to describe or comprehend that anyone who had an inkling would be embarrassed by diminishing 'God' to any terms necessary to describe 'God'. Either one experiences 'God' to the maximum of his/her capacities in the most intimate, personal way possible, or one is merely spouting insulting, belittling adjectives and nouns.
The nice, warm feeling of religion is understandable, even if it is more suited to the childish type of assurances like the Santa Claus story. It is not suited to the mature human animals we should be after so many thousands of years of written history. Every religion says 'God' is beyond our scale of comparisons, then the religion sets about imposing images of 'God', even if only mental ones. If 'God' is all, then 'God' is not only great, but also small. Every thing and everyone exits in 'God' and everything that can be is part of 'God' and creation. That means all the formulas imposed on 'God' aimed at persuading 'God' are only expressions of not accepting that whatever happens is 'God', right in front of one, in fact inside one as well. It cannot be anything else. Nothing could be outside the true 'God'.
This is not saying what 'God' would be; it is identifying what 'God' could not be.