Well, that is an old tale, but the Catholic Church was the first church ... of Christ and gave us our Bible. Protestants (named so for protest-ants) disagreed and broke off with the Church. Their right of course. They are now split into many disagreeing denominations. Again, up to them.
I would never say that anyone who believes in jesus Christ is not a Christian, but you can do that if you wish. Have a great day. There are, of course, many "misunderstandings" about the Church. So be it. We are all welcome to have our 'opinions' on these issues.