The word Christian has been often used to refer to Protestants loosely and mostly now colloquially, but strictly speaking, they are not Christians and not true ones at that.
In my experience, Protestants do not think much beyond an oversimplified way of thinking and objectively believe heresy by default, e.g. against papal primacy or purgatory. They are taught the heresy of "sola Scriptura," and many a Catholic today has sadly fallen into a tendency to that to the detriment of their being lack of knowledge of the other font of divine revelation, i.e. Tradition. Even so, Catholics and Protestants may not have an adequate knowledge of the Bible either. Some Protestants might have a better sense of objective truth though than most Catholics today, but they still hold to errors and heresies. Often, as what was told to me by someone years ago, the barrier to conversion is a moral issue like a marital situation involving divorce and shared custody of children.