Irreligion may be defined as the absence of religion, an indifference towards religion, a rejection of religion, or hostility towards religion. When characterized as the rejection of religious belief, it includes atheism and secular humanism. When characterized as hostility towards religion, it includes antitheism, anticlericalism and antireligion. When characterized as indifference to religion, it includes apatheism. When characterized as the absence of religious belief, it may also include agnosticism, ignosticism, nontheism, religious skepticism, and freethought. Irreligion may even include forms of theism depending on the religious context it is defined against, as in 18th century Europe where the epitome of irreligion was deism.

Sixteen percent of the world population (1.1 billion people) are considered non-religious. Some evidence suggests that the fastest growing religious status in the United States is "no religion".

Alan Wilson Watts (6 January 1915 – 16 November 1973) was a British philosopher, writer, and speaker, best known as an interpreter and populariser of Eastern philosophy for a Western audience. Born in Chislehurst, he moved to the United States in 1938 and began Zen training in New York. Pursuing a career, he attended Seabury-Western Theological Seminary, where he received a master's degree in theology. Watts became an Episcopal priest but left the ministry in 1950 and moved to California, where he joined the faculty of the American Academy of Asian Studies.

Living on the West Coast, Watts gained a large following in the San Francisco Bay Area while working as a volunteer programmer at KPFA, a Pacifica Radio station in Berkeley. Watts wrote more than 25 books and articles on subjects important to Eastern and Western religion, introducing the then-burgeoning youth culture to The Way of Zen (1957), one of the first bestselling books on Buddhism. In Psychotherapy East and West (1961), Watts proposed that Buddhism could be thought of as a form of psychotherapy and not just a religion. Like Aldous Huxley before him, he explored human consciousness in the essay, "The New Alchemy" (1958), and in the book, The Joyous Cosmology (1962).

Greg M. Epstein is the current secular humanist chaplain at Harvard University, and is a published author on the subject of secular humanism.

Epstein was born February 4, 1977 and grew up in the ethnically-diverse neighborhood of Flushing, Queens, New York. His parents, though Jewish, were not very religious, and he attended services with them only occasionally, usually during Jewish holidays or festivals. He describes this experience as one of the foundations for his later interest in Humanistic Judaism.

While attending the Stuyvesant High School in Manhattan, Epstein studied Buddhism and Taoism. After graduating from high school, he enrolled in the University of Michigan in Ann Arbor. As part of his undergraduate studies in the University of Michigan's College of Literature, Science, and the Arts, he spent a year in Taiwan in an effort to further his knowledge of Zen Buddhism through readings in Chinese and direct contact with Zen practitioners. Becoming disenchanted with Eastern religions during this experience, Epstein returned to the U.S. and completed his Bachelor of Arts in Religion and Chinese from the University of Michigan. He then went on to complete a Master of Arts in Judaic Studies, also from the University of Michigan.