The short answer
Religion is usually a shared system of beliefs, practices, ethics and community, often with institutions and recognized authorities. Mysticism is the pursuit of direct, personal experience of the ultimate. Mysticism commonly grows inside a religion, so the two are better seen as overlapping than as opposites.
What religion typically includes
Religions commonly involve:
- Teachings or doctrines, often grounded in scripture or tradition
- Shared rituals, worship and holy days
- Moral guidance
- A community and, often, leadership or authority structures
What mysticism emphasizes
Mysticism emphasizes lived encounter over inherited belief: the hope of knowing the divine or ultimate reality directly. Its language is often symbolic, poetic or paradoxical because mystics report that ordinary words fall short. For more, see what mysticism is.
Where they overlap
Most well-known mystics were religious people who used the vocabulary, texts and practices of their traditions. Examples include Christian mystics, Sufis and Jewish Kabbalists. In many traditions, mystical practice is seen as the heart of the faith, not a departure from it.
Where they come into tension
Because mystics claim direct access, institutions have sometimes been wary. A mystic’s insight may seem to relativize doctrine or authority, and some mystics have faced censure. Meister Eckhart’s writings were partly condemned after his death, and the Sufi al-Hallaj was executed. Other mystics remained fully accepted, some as saints. Whether tension arises depends on the era, the tradition and the person.
Mysticism outside religion
Some people have mystical-type experiences without belonging to any religion, and some describe their outlook as spiritual but not religious. See mysticism vs spirituality for how those terms differ, and what a mystical experience is for the experience itself.