It was their doctrines that were denounced. But both men were baptized Catholics and Luther an ordained priest. As for their followers, that would be those who openly professed such doctrines. In Germany and elsewhere, the common people usuallu had no choice as they were required to follow the dictates of their local authorities. This would be less true of the sects, who were persecuted by both Catholics and Lutherans. Freedom of religion —as a concept— was anathema even to the sectarians. They did not believe any man had the right to err about the true doctrine of Christ.
RE: As for their followers, that would be those who openly professed such doctrines.
There are MILLIONS of Luther and Calvin followers now who OPENLY profess their doctrines.
Luis Palau being one of them ( ask him for instance if he believes in Sola Scriptura, I am 100% certain he would say YES. Why do I say that? I heard him say so before ).
Ask Palau directly if he believes that Pope Francis should be THE ( not ‘a’ ) representative of Christ on earth. If he were honest to his Evangelical Heritage, he would say Francis is ‘a’ representative, but not ‘the’ representative of Christ.
Vatican I condemns that belief, but Vatican II does not.
To be consistent with your statement ‘As for their followers, that would be those who openly professed such doctrines.’, men like Palau would be under Vatican I anathema ( bit not Vatican II ).