Simplify the following text for a Grade 11 native English-speaking person.
Original: His chief foreign policy objective was to check the power of the Austro-Spanish Habsburg dynasty ; although a Roman Catholic cardinal , he did not hesitate to make alliances with Protestant rulers .
Simplified: His chief foreign policy objective was to check the power of the Austro-Spanish Habsburg dynasty , and to ensure French dominance in the Thirty Years ' War . Although he was a cardinal , he did not hesitate to make alliances with Protestant rulers in attempting to achieve this goal .