If Europe divided into Protestant and Catholic great-power blocs

How would the First World War change if Europe's Protestant and Catholic monarchies each united under one ruler?

The Britain-Germany bloc is favoured through sea access and combined forces. France and Orthodox monarchies remain outside the initial grouping, and Belgium remains a British security concern.

The hypothetical unites Europe's Protestant monarchies under one monarch and its Catholic monarchies under another before the First World War. Republican France and the Orthodox monarchies fall outside that initial division. A Britain-Germany alignment is favoured because Germany would retain access to seaborne supplies and the combined navies would obstruct overseas intervention. France might choose to join that stronger side despite the religious labels. The fate of Belgium would remain a British security concern because of its coast and anchorages.