The Aztec religion is a very sensitive subject to some. Every culture and religion has its own beliefs and traditions. Many still practice their traditions, but only those that are permitted by the law. In the Aztec religion, sacrifice is a major part of their religious rituals. The Aztec religion did not discriminate among the victims to be sacrificed. Women, men, and children were sacrificed. Some of who volunteered did it because after their death they believed they would be taken to a more beautiful place. Slaves and prisoners would also take part in these ceremonies as well.
The Aztec calendar plays an important role in sacrifice and religion. Every 52 years the tanalpohualli and the xiupohualli calendars would align. This marked what was known as the mesoamerican century. "Every one of these centuries was marked by xluhmolpilli, "the binding of the years." (www.uwgb.edu) The festival lasted 12 days and included fasting as a symbol of penitence. The lights would be extinguished on the first day and on the last day they would be lit once again with the new fire, only after the sacrifice of a prisoner. A priest would remove the prisoner's heart and replace it with a piece of wood.
In other occasions when they would remove the hearts of their victims, "they believed that good gods could prevent bad gods from doing bad things. They also believed that they got their strength from human blood and hearts so they had sacrifices in order to keep their gods strong." (www.cyberessays.com) "Human sacrifice became widely used as gifts to the gods during the middle of the 15th century. An estimated 10,000-15,000 people were sacrificed each year." (www.uwgb.edu) Some sacrifices ranged from hours to days. They had different gods, which also include Uttzilpochtli (the sun god), Coyolxauhqui (the moon goddess), Tlaloc (the rain god), and Quezalcoatl (the inventor of the calendar and the writing). Although these people performed sacrifices it was only because they believed that something good would be brought amongst their people and gods. It may sound too brutal to some people but their hearts were in the right place.
Information on theAztec calendar.