Check out some of these audio books focusing on World Religions and Philosophies:
Buddhism By Dr. Winston King
Buddhism began with Gotama the Buddha in the sixth century BCE and has developed two chief forms: Theravada (or Hinayana) is found especially in Sri Lanka, Burma, and Thailand: Mahayana is found in Japan, China, Korea, and Indochina. Zen, a more recent form of Buddhism, is found throughout the world. Some believe Buddhism is not properly understood as a religion, though this presentation describes its religious qualities: a belief in transcendent reality, sacred scriptures, monastic life, and views on a future life and the goal of human existence.
Islam By Dr. Charles Adams
Islam today is a rapidly growing religion: Indonesia, the most populous Islamic land, has well over 100 million Muslims. Islam means "submission to the will of God"; Muslims are "submitters" to God's will as it was communicated to the prophet Muhammad in a series of divine revelations. Islam began in the seventh century, and had evolved into various forms, including Sunni and Shi'ah Muslims, Sufi mystics, and others. It has been and remains one of the most significant influences in the world.
Judaism By Dr. Geoffrey Wigoder
Judaism is more than a religion; it is a civilization including a people, a language, unique laws, a system of ethics, custom, a homeland, and a theology. Jews worship one God and obey a wide-ranging and vigorous moral law centered around the Torah, God's teaching or instruction.
Awakened Mind System By Dr. Jeffrey Thompson
We all seek a state of higher consciousness that awakens and enlivens our whole being. Masters of meditation and yoga, great artists, inventors, and highly accomplished people in many walks of life have learned to Develop and Live from such a state. Awakened Mind System
African and African-American Religion By Dr. Victor Anderson
The religious ideas and practices of African peoples have much in common with each other, and with related religions in the Caribbean and the Americas. African Islam and African Christianity have developed separately since their earliest time in Ethiopia, Egypt, and the Sudan. African and African-American Religion
Listening to these will give you a greater appreciation and understanding of religions around the world and how they influence Christianity.