I’m not sure why this particular website has been banned, but if it was banned by the German government it probably contained pro-Nazi information or was a mouthpiece for any of the banned far right partys in that country.
Germans generally enjoy free speech, but anything relating to the Nazi-era, such as insignias, flags, uniforms, the Hitler salute etc. is forbidden to be used in a manner that would be seen as supporting the Third Reich or downplaying its crimes. There are also a few political partys that have been banned due to the prevalance of Nazis or their particular politics.
Other than that Germans have free speech laws that allow for many of the same freedoms found in the US and presumably Australia. Unless a religious website started to take on Nazi views it is doubtful it would ever be banned, even if the majority of Catholics found it distasteful or offensive.
ChadS