What is the God-instituted Christianity of today?
Fair enough. It's whatever the Bible defines it to be. Fundamentally it's based on the Christ who came into the world to save His people from their sins. The God-instituted Christianity of today is what is practiced by those who have the Bible alone as their standard reference material. Legitimate variations exist only insofar as fallible men are required to interpret the objective statndard. This is different from those who fundamentally reject the objective standard, or supplement that standard with traditions of men that they raise to the same level as the objective standard. Any legitimate definition of Christinity must first and foremost reference the Bible.
Now, to get back to the question, using the information I've provided which I'm sure was helpful, "What is the authentic, God-instituted expression of Judaism today?"
I don't want this question to slip away since you were the one who raised the concept of "different flavors" of Judaism as if all expressions are equally legitimate. Chocolate or vanilla, it really doesn't matter. Is that so?