You are the one claiming the Holy Office contradicted Mortalium Animos. You've made no specific argument in support of your "theory."
Argument: a process of reasoning; series of reasons; a statement, reason, or fact for or against a point.
This is my "argument":
- Mortalium Animos, and, well, the Bible and other past Holy Office decrees,
condemn any and all form of communicatio in divinis with non-Catholics, which of course includes PRAYER.
- The 1949 Instruction on Ecuмenism
allows praying the Pater Noster or any other approved Church prayer with heretics and non-Catholics.
Explain.