Final answer:
Henry IV of France summarized his decision to convert to Catholicism with the quote 'Paris is worth a mass.'
Step-by-step explanation:
The five-word quote that Henry IV of France supposedly summarized his decision to convert to Catholicism before being crowned king in 1594 is 'Paris is worth a mass.'
This quote signifies Henry IV's recognition of the political importance of Catholicism in France and his willingness to embrace it for the sake of unity and stability in the country.