[metmom]

Excommunication is an act precipitated by ones own choices and actions. It does not require formal Church acknowledgment and recognition. Hitler was, by his own actions, not in Communion with the Church; excommunicated.

Then the same could be said about Luther. But the Catholic church went out of its way to make it official for him.

Why for him and not for Hitler?

[Natural Law]

"Why for him and not for Hitler?"

Excommunication was not necessary for Hitler because he has long since renounced his Catholicism and abandoned the Church. At no time time did Hitler claim to be acting on behalf of or in compliance with the Church. His public actions further reinforced his position. Unlike Hitler, Luther continued to claim to be Catholic and had to be publicly thrown out.