You don't need to be religious to enjoy the calming atmosphere of Maputo Cathedral. Find out when the next service starts or when it's open for general viewing.
You'll be spoiled for sightseeing choice when visiting Central C. Maputo Cathedral is a good place to kick off here, but there are plenty of other interesting places to experience. Eduardo Mondlane University, Maputo Central Market, and Maputo City Hall are close to the principal church and will round out your day nicely.