Interfaith dialogue refers to cooperative, constructive, and positive interaction between people of different religious traditions (i.e. "faiths") and/or spiritual or humanistic beliefs, at both the individual and institutional levels. It is distinct from syncretism or alternative religion, in that dialogue often involves promoting understanding between different religions or beliefs to increase acceptance of others, rather than to synthesize new beliefs.

The Archdiocese of Chicago's Office for Ecumenical and Interreligious Affairs defines "the difference between ecumenical, interfaith, and interreligious relations", as follows:

• "ecumenical" as "relations and prayer with other Christians",
• "interfaith" as "relations with members of the 'Abrahamic faiths' (Jewish, Muslim and Christian traditions)," and
• "interreligious" as "relations with other religions, such as Hinduism and Buddhism".

Some interfaith dialogues have more recently adopted the name interbelief dialogue, while other proponents have proposed the term interpath dialogue, to avoid implicitly excluding atheists, agnostics, humanists, and others with no religious faith but with ethical or philosophical beliefs, as well as to be more accurate concerning many world religions that do not place the same emphasis on "faith" as do some Western religions. Similarly, pluralistic rationalist groups have hosted public reasoning dialogues to transcend all worldviews (whether religious, cultural or political), termed transbelief dialogue. To some, the term interreligious dialogue has the same meaning as interfaith dialogue. Neither are the same as nondenominational Christianity. The World Council of Churches states: “Following the lead of the Roman Catholic Church, other churches and Christian religious organizations, such as the World Council of Churches, have increasingly opted to use the word interreligious rather than interfaith to describe their own bilateral and multilateral dialogue and engagement with other religions. [...] the term interreligious is preferred because we are referring explicitly to dialogue with those professing religions – who identify themselves explicitly with a religious tradition and whose work has a specific religious affiliation and is based on religious foundations."

Throughout the world there are local, regional, national and international interfaith initiatives; many are formally or informally linked and constitute larger networks or federations. The often quoted "There will be no peace among the nations without peace among the religions. There will be no peace among the religions without dialogue among the religions" was formulated by Hans Küng, a Professor of Ecumenical Theology and President of the Global Ethic Foundation. Interfaith dialogue forms a major role in the study of religion and peacebuilding.