Thomistic Essence and Existence as the Primary Christian Truth

Go here for a discussion of how the Thomistic doctrine of esse and essentia is a primary truth of Christian metaphysics, (conveniently) indemonstrable. What I can't get my mind around is the claim that every Christian thinker thinks this. Perhaps despite all the exposition of Aquinas it is not the specifically Thomistic view that is being argued for, but rather just that essence and existence are distinct in some unspecified way? For otherwise, how can we account for the dozens of scholastic theories on the topic?