Like Chino said, Carnival does have to do with the Catholic religion. That's why you have "Fat Tuesday" during Mardis Gras. It's the last chance to "let go" before the start of Lent on Ash Wednesday. One of the traditions of Lent is to give up something for those 40 days. Like deciding you're going to stop eating chocolate for that time. It can be anything that you enjoy, you have to give it up. It's to symbolize the sacrifice that God and Jesus Christ made for us. So you have that Carnival time before Lent begins. I hope that made sense. It's late and I'm tired.