When we say that Christianity was an esoterism, we are speaking not in reference to its structure, at least not primarily, but in relation to its content. The types of truths Christ brought to light are those normally dealt with via esoterism in other faiths, except with the Gospel we find them first and foremost, and from the beginning, and the exoterism built only later. Christianity worked from the center outward. This created difficulties, as I’ll explain below. But this is very different from the “esoterism of structure” that we find in, for example, Hinduism or Islam, where the esoteric knowledge and the exoteric dogmas are organized side-by-side and have never been unseparated.
This unique ordering of things in their development—a preacher of esoterism with a close and private group of followers who spread a doctrine that was esoteric in content, which then adapted itself to the common people with an appropriate exoteric formulation—is why so many of the words spoken by Christ and by the early Christian fathers seem incomprehensible or at odds with what Christians typically understand to be the content of their faith.