The Catholic Church is the largest non-government provider of health care services in the world. It has around 18,000 clinics, 16,000 homes for the elderly and those with special needs, and 5,500 hospitals, with 65 percent of them located in developing countries.Calderisi, Robert. Earthly Mission - The Catholic Church and World Development; TJ International Ltd; 2013; p.40 In 2010, the Church's Pontifical Council for the Pastoral Care of Health Care Workers said that the Church manages 26% of the world's health care facilities. The Church's involvement in health care has ancient origins.

Jesus Christ, whom the Church holds as its founder, instructed his followers to heal the sick.Matthew 10:8 The early Christians were noted for tending the sick and infirm, and Christian emphasis on practical charity gave rise to the development of systematic nursing and hospitals. The influential Benedictine rule holds that "the care of the sick is to be placed above and before every other duty, as if indeed Christ were being directly served by waiting on them". During the Middle Ages, monasteries and convents were the key medical centres of Europe and the Church developed an early version of a welfare state. The USCCB holds that an increase in the acceptance of Hippocratic Oath violations leads to killing rather than seeking cures.USCCB. “The Right of the Dying to Live.” United States Catholic Catechism for Adults, 2nd ed., vol. 1, United States Conference of Catholic Bishops, Washington D.C., 2020, pp. 398–399. Cathedral schools evolved into a well integrated network of medieval universities and Catholic scientists (many of them clergymen) made a number of important discoveries which aided the development of modern science and medicine.

Albert the Great (1206–1280) was a pioneer of biological field research and is a saint within the Catholic Church; Desiderius Erasmus (1466–1536) helped revive knowledge of ancient Greek medicine, Renaissance popes were often patrons of the study of anatomy, and Catholic artists such as Michelangelo advanced knowledge of the field through sketching cadavers. The Jesuit Athanasius Kircher (1602–1680) first proposed that living beings enter and exist in the blood (a precursor of germ theory). The Augustinian Gregor Mendel (1822–1884) developed theories on genetics for the first time. As Catholicism became a global religion, the Catholic orders and religious and lay people established health care centres around the world. Women's religious institutes such as the Sisters of Charity, Sisters of Mercy and Sisters of St Francis opened and operated some of the first modern general hospitals.

While the prioritization of charity and healing by early Christians created the hospital, their spiritual emphasis tended to imply "the subordination of medicine to religion and doctor to priest". "Physic and faith", wrote historian of medicine Roy Porter "while generally complementary... sometimes tangled in border disputes." Similarly in modern times, the moral stance of the Church against contraception and abortion has been a source of controversy. The Church, while being a major provider of health care to HIV AIDS sufferers, and of orphanages for unwanted children, has been criticised for opposing condom use. Due to Catholics' belief in the sanctity of life from conception, IVF, which leads to the destruction of many embryos, surrogacy, which relies on IVF, and embryonic stem-cell research, which necessitates the destruction of embryos, are among other areas of controversy for the Church in the provision of health care.

Theological basis:

Catholic social teaching urges concern for the sick. Jesus Christ, whom the church holds as its founder, placed a particular emphasis on care for the sick and outcast, such as lepers. According to the New Testament, he and his Apostles went about curing the sick and anointing of the sick.Geoffrey Blainey; A Short History of Christianity; Penguin Viking; 2011 According to the Parable of the Sheep and the Goats, which is found in Matthew 25, Jesus identified so strongly with the sick and afflicted that he equated serving them with serving him:

In a 2013 presentation to its twenty-seventh international conference in 2013, the President of the Pontifical Council for the Pastoral Care of Health Care Workers, Zygmunt Zimowski, said that "The Church, adhering to the mandate of Jesus, 'Euntes docete et curate infirmos' ( 10:6-8, Go, preach and heal the sick), during the course of her history, which by now has lasted two millennia, has always attended to the sick and the suffering."

In orations such as his Sermon on the Mount and stories such as the Parable of the Good Samaritan, Jesus called on followers to worship God (Romans 12:1–2) through care for one's neighbor: the sick, hungry and poor. Such teachings formed the foundation of Catholic Church involvement in hospitals and health care.

According to James Joseph Walsh, writing in the Catholic Encyclopedia:

The Benedictine rule, which led the profusion of medieval hospitals founded by the Church, requires that "the care of the sick is to be placed above and before every other duty, as if indeed Christ were being directly served by waiting on them".

History

Antiquity Ancient Greek and Roman medicine developed solid foundations over seven centuries, creating, Porter wrote, "the ideal of a union of science, philosophy and practical medicine in the learned physician...". But Greek and Roman religion did not preach of a duty to tend to the sick. Christianity emerged into this world as a Jewish sect in the mid-1st century and early Christians from the outset went about tending the sick and infirm. Their priests were often also physicians. St Luke the Evangelist, credited as one of the authors of The New Testament, was a physician. Christian emphasis on practical charity was to give rise to the development of systematic nursing and hospitals after the end of the persecution of the early church.

The early Christian outlook on sickness drew on various traditions, including Eastern asceticism and Jewish healing traditions, while the New Testament wrote of Jesus and his Apostles as healers. Porter wrote: "While suffering and disease could appear as chastisement of the wicked or a trial of those the Lord loved, the Church also developed a healing mission". Pagan religions seldom offered help to the sick, but the early Christians were willing to nurse the sick and take food to them. Notably during the smallpox epidemic of 165–180 AD and the measles outbreak of around 250 AD, "In nursing the sick and dying, regardless of religion, the Christians won friends and sympathisers", wrote historian Geoffrey Blainey.

Hospitality was considered an obligation of Christian charity and bishops' houses and the valetudinaria of wealthier Christians were used to tend the sick. Deacons were assigned the task of distributing alms, and in Rome by 250 AD the Church had developed an extensive charitable outreach, with wealthy converts supporting the poor. It is believed that the first church hospitals were constructed in the East, and only later in the Latin West. An early hospital may have been built at Constantinople during the age of Constantine by St. Zoticus. St. Basil built a famous hospital at Cæsarea in Cappadocia, later called Basileias, which "had the dimensions of a city". In the West, Saint Fabiola founded a hospital at Rome around 400. Saint Jerome wrote that Fabiola founded a hospital and "assembled all the sick from the streets and highways" and "personally tended the unhappy and impoverished victims of hunger and disease... washed the pus from sores that others could not even behold"

Several early Christian healers are honoured as Saints in the Catholic tradition. Cosmas and Damian, brothers from Cilicia in Asia Minor, supplanted the pagan Asclepius as the patron saints of medicine and were celebrated for their healing powers.." Said to have lived in the late third century AD and to have performed a miraculous first leg transplant on a patient, and later martyred under the Emperor Diocletian, Cosmas and Damian appear in the heraldry of barber-surgeon companies.." Notable contributors to the medical sciences of those early centuries include Tertullian (born 160 AD), Clement of Alexandria, Lactantius and the learned St. Isidore of Seville (d. 636). St. Benedict of Nursia (480) emphasised medicine as an aid to the provision of hospitality. The martyr Saint Pantaleon was said to be physician to the Emperor Galerius, who sentenced him to death for his Christianity. Since the Middle Ages, Pantaleon has been considered a patron saint of physicians and midwives.

The administration of the Eastern and Western Roman Empires split and the demise of the Western Empire by the sixth century was accompanied by a series of violent invasions, and precipitated the collapse of cities and civic institutions of learning, along with their links to the learning of classical Greece and Rome. For the next thousand years, medical knowledge would change very little.." A scholarly medical tradition maintained itself in the more stable East, but in the West, scholarship virtually disappeared outside of the Church, where monks were aware of a dwindling range of medical texts.." The legacy of this early period was, in the words of Porter, that "Christianity planted the hospital: the well-endowed establishments of the Levant and the scattered houses of the West shared a common religious ethos of charity.".

Middle Ages

Geoffrey Blainey likened the Catholic Church in its activities during the Middle Ages to an early version of a welfare state: "It conducted hospitals for the old and orphanages for the young; hospices for the sick of all ages; places for the lepers; and hostels or inns where pilgrims could buy a cheap bed and meal". It supplied food to the population during famine and distributed food to the poor. This welfare system the church funded through collecting taxes on a large scale and possessing large farmlands and estates.Geoffrey Blainey; A Short History of Christianity; Penguin Viking; 2011; pp 214-215. It was common for monks and clerics to practice medicine and medical students in northern European universities often took minor Holy orders. Mediaeval hospitals had a strongly Christian ethos and were, in the words of historian of medicine Roy Porter, "religious foundations through and through"; ecclesiastical regulations were passed to govern medicine, partly to prevent clergymen profiting from medicine.

After a period of decline, the Holy Roman Emperor Charlemagne had decreed that a hospital should be attached to each cathedral and monastery. Following his death, the hospitals again declined, but by the tenth century monasteries were the leading providers of hospital work – among them the Benedictine Abbey of Cluny. Charlemagne's decree required each monastery and Cathedral chapter to establish a school and in these schools medicine was commonly taught. Gerbert of Aurillac ( – 12 May 1003), known to history as Pope Sylvester II, taught medicine at one such school. Petrus of Spain (1210–1277) was a physician who wrote the popular Treasury of the Poor medical text and became Pope John XXI in 1276.