As the crusaders fought to defend Christianity, members of the Order nowadays live in spiritual solidarity by the witness of their Christian lives and by the promotion of ecumenism. Women have been admitted as members of the Order since at least 1287, contributing both spiritually and practically. The original Roman Catholic foundation has in recent centuries expanded to include lay and clerical members from all the major Christian traditions. These include a small number of professed knights, who choose to perfect their chivalric investiture through the practice of a rule of life adapted for lay persons. Since many of the members were of noble birth, wealthy benefactors have always patronised the Order, enabling it with the support of papal and royal privileges to expand its work across Europe and later to the new world. The vicissitudes of history with divisions and abuses have caused the Order of St Lazarus over the centuries, like the Church itself, to evolve and reform. Nowadays there are numerous associations using similar names and symbols, which, although not part of the Order, do observe aspects of the 'green cross' tradition and usually perform some charitable work. The heraldic motto 'Atavis et Armis' - valour in the spirit of our forefathers - encompasses the essential and enduring noble values of courage and tradition. 

The Order takes its name from the biblical Lazarus. There are two mentioned in the New Testament, the first being the brother of Martha and Mary, a friend whom Jesus raised from the dead (John 11:1-44). This miracle is recounted principally as a sign that Jesus really is the power of life evident in his own resurrection. It is also a fulfilment of his prophecy in John 5:28-29 that 'the hour is coming when the dead will leave their graves at the sound of his voice'. Then there is the parable of the rich man and Lazarus (Luke 16:19-31), which also treats themes of illness, death and resurrection. The beggar named Lazarus was 'full of sores' and so presumably suffering from leprosy, the disease then being endemic. The two stories were probably both taken into account when the dedication of St Lazarus was chosen for the original Jerusalem hospital. In succeeding centuries, Lazarus became the patron saint of lepers and the word 'lazaretto' came to denote a leprosarium. The feast of St Lazarus is generally observed on 17 December in Western Christianity and the Saturday before Easter in Orthodoxy.

In order to prevent theft on returning from the Holy Land after the fall of Saint Joan of Acre, King Philip IV the Fair gave the Order of Saint Lazarus his “special guard and protection” at Poitiers in July 1308. Since then, successive heads of the Royal House of France assumed that pledge of protection until King Charles X in 1830.

In its formative years of being under the Spiritual Protection of Greek Catholic Patriarchs of Jerusalem, the Order of Saint Lazarus was confirmed by Pope Alexander IV, in the Bull given in Naples on 11 April 1255. Having forged new links with the Greek-Melkite Catholic Patriarchate and returning to its eastern origins in 1841, the Order of Saint Lazarus found its official Temporal Protection from the Head of the Royal House of France on 12 September 2004 and re-established a link directly with the Catholic Church on 2 February 2005.