Calormene religion

The Calormene religion was the official belief system of Calormen, an empire within the World of Narnia.

Pantheon
The Calormene religion was polytheistic, meaning that it contained multiple deities. The best-known of these deities was Tash, the powerful patriarch god who had a vulture-like head and four arms. The Tisroc, the Calormene head of state, claimed descent from Tash. Aravis Tarkeena mentioned that her father's family - and by extension herself - was "descended in a right line from the god Tash". While this may have simply been metaphorical (Calormene storytelling is typically highly embellished), it could indicate that certain noble families in Calormen possess kinship ties to the Tisroc (indeed, Aravis claimed in the same breath that her ancestors included a Tisroc).

Two other named deities in the Calormene pantheon were Azaroth and Zardeenah, the latter being a goddess of the night who also watched over unmarried women.

Description
While The Chronicles of Narnia do not describe the Calormene religion in great detail, they offer a number of clues that give insight into the belief system. For example, Tirian described his childhood visit to Tashbaan and noted that the temple of Tash contained a statue of the god, indicating that the religion made use of idols (at least of Tash himself). It was also mentioned that the calendar of the religion included an Autumn Feast (the time Aslan decreed that Prince Rabadash must stand in the temple of Tash to be cured of his donkey's form).

Aravis described a ritual performed by Calormeme women in preparation of marriage: the bride-to-be would go into the wilderness and perform three days of ceremonial sacrifices to Zardeenah, as an indication that they were leaving the goddess' service when they married.

Trivia
It has been widely speculated that C. S. Lewis was comparing the Calormene religion to Islam (though its followers, Muslims, are strict monotheists, not polytheists); Lewis, though, had also praised aspects of Islam in some of his works and the name "Aslan" means "lion" in the languages of many Muslim countries.