If someone has doubts about what many consider foundation principles of Judiasm does that make him a heretic? Or is it only if a person comes to a conclusion that it is false at which point he becomes a heretic?
The point at which he rejects anyone of the Rambams 13 Ani Mamins you either belive them or not it is binary. It is totally ok to question but only if you are searching for answers. Only you can know truly if you are a kofer. You being the theoretical subject.