Asceticism has been historically observed in many religious traditions, including Buddhism, Jainism, Hinduism, Christianity, and Judaism. Contemporary mainstream Islam practices asceticism in the form of fasting during Ramadan by abstaining from all sensual pleasures, food & water from sunrise until sunset. The observation of fasting during Ramadan is purely done for God and to increase one's spiritual connection with God; it is compulsory on all Muslims to fast as it is one of the Five Pillars of Islam. The Sufism sects tradition has included strict asceticism throughout history. The practitioners of these religions abandoned sensual pleasures and led an abstinent lifestyle, in the pursuit of redemption, salvation or spirituality. Asceticism is seen in the ancient theologies as a journey towards spiritual transformation, where the simple is sufficient, the bliss is within, the frugal is plenty.
The adjective "ascetic" derives from the ancient Greek term askēsis, which means "training" or "exercise". The original usage did not refer to self-denial, but to the physical training required for athletic events. Its usage later extended to rigorous practices used in many major religious traditions, in varying degrees, to attain redemption and higher spirituality.
Dom Cuthbert Butler classified asceticism into natural and unnatural forms:
Self-discipline and abstinence in some form and degree are parts of religious practice within many religious and spiritual traditions. Ascetic lifestyle is associated particularly with monks, nuns, fakirs in Abrahamic religions, and bhikkhus, munis, sannyasis, yogis in Indian religions.
Christian authors of late antiquity such as Origen, St. Jerome, St. Ignatius, John Chrysostom, and Augustine interpreted meanings of Biblical texts within a highly asceticized religious environment. Scriptural examples of asceticism could be found in the lives of John the Baptist, Jesus, the twelve apostles and the Apostle Paul. The Dead Sea Scrolls revealed ascetic practices of the ancient Jewish sect of Essenes who took vows of abstinence to prepare for a holy war. An emphasis on an ascetic religious life was evident in both early Christian writings (see the Philokalia) and practices (see hesychasm). Other Christian practitioners of asceticism include individuals such as Simeon Stylites, Saint David of Wales and Francis of Assisi.