This is Holy Week, the most sacred time of year for Christians. It is the time they mark the betrayal, trial, and crucifixion of Jesus, and a week that culminates in Easter Sunday, the day Christians believe Jesus rose from the dead. Above is a definition of holy week i copied from a website. I think around here they should change the name to drunken idiot week or even more drunken idiots with louder music and it must last longer than a week as it's started already. I am not a religious person and when i see this it makes me glad i am not.
Holy week is different here than my native southern California. Here everything is opening and operating on Easter Sunday, but closed on the Thursday and Friday before. Reading the posts around town will help you understand what is open and what is closed. Do your banking in advance or you may not have enough pocket money to celebrate with your favorite "Boulevard lady"... The week's activities may be more influenced by alcohol than religious beliefs as you mentioned for some people here, but then again for some that could be said of any week. . A little pre-planning of your activities (particularly necessary financial transactions) and you can survive the week, but just be aware it is a unique week in the Philippines, everything is a little different that week.