Teresa de Ávila lived in tumultuous times. Lutheranism was tearing Christian Europe apart. In France and in the Spanish territories to the North, Catholics and Protestants were at war. In the Americas, Spanish soldiers were facing untold dangers advancing the interests of the Crown, and one by one, Teresa's seven brothers joined their ranks. In Spain, the Inquisition persecuted those suspected of heterodoxy or spurious raptures, especially women. As an ecstatic and the daughter and granddaughter of conversos (converts from Judaism), Teresa was constantly under suspicion. Furthermore, opposition from the Carmelite hierarchy to the new religious order she founded, the Discalced Carmelites, put her squarely on the defensive. And during the last years of her life, the catarro universal—a global pandemic that, like Covid-19, spread like wildfire—claimed the lives of several of her close friends. In the midst of often harrowing circumstances, Teresa (known in the Spanish-speaking world as Santa Teresa de Jesús) sought refuge in her own soul—her “interior castle”—where she found spiritual peace.

Long before Teresa was born, many in Europe recognized the need for religious reform. By the late middle ages, the Church had become highly bureaucratic and materialistic, and religious practice was often reduced to a series of empty rituals. Parents frequently placed some of their daughters in female convents at an early age, often as young as 3 or 4, to avoid paying a marriage dowry, and some of their sons in male convents because, due to primogeniture, they were ineligible to inherit property. Consequently, these institutions were often overcrowded and inhabited by men and women with no real religious vocation. To counteract this situation, during the twelfth and thirteenth centuries, new orders were formed that stressed prayer over ritual and sought to foster an authentic relationship with God among their members. Some of the mendicant orders (those that forbid personal property) split into “conventuals,” who maintained a “mitigated” or more relaxed lifestyle, and “observants,” who adopted an “unmitigated” regime designed to promote genuine piety.

However, the spiritual reform was not limited to the religious orders. In the Low Countries, a new movement called the devotio moderna was gaining momentum among the laity as well as the reformed clergy. The devotio moderna was launched around 1374 by Geert Groote (1340–1384), a Dutch Roman Catholic deacon who believed that religious practices had become corrupted and void of meaning.