You needn't be of strong faith to appreciate the calming atmosphere of Dili Cathedral. Look up when the next mass starts or when you can go for a wander through.
Situated in Dili, this principal church is worth including in your schedule. But you'll find lots more to discover in this area. National University of East Timor, Cristo Rei of Dili, and Arte Moris aren't too far away from Dili Cathedral.