Those who would reject the existence on one holy catholic and apostolic (which, for me is found in the Roman Catholic and Eastern Orthodox Churches) find themselves in a tight spot when pinned down abou the basics.
At some level they know they need to align with the Christologic definitions that the councils delivered. At least, for me, when I actually read the councils, they proclaimed what I had been taught about who Jesus was (and was not).
I had no clue, until I began studying, that the questions were settled hundreds of years ago and that the answers were what I already believed. Of course, by then, I was honestly and passionately seeking - not defending a position.