Origin of Saints in Christianity:
The idea of sainthood is not described in either the Jewish or Christian scriptures, but there is evidence of Christian veneration of Jesus and his disciples at a very early stage of Christianity. Later, people persecuted and martyred for their Christian faith were also venerated. After the general persecutions ended, people who lived their lives as monks or as generally holy people were also venerated. All of this is believed to have become the basis for the concept of Christian sainthood.
Martyrs and Martyrdom in Christianity:
A martyr suffers persecution or death because of their religious faith. The word martyr comes from the Greek martyrs, which means witness and refers to how one witnesses for their faith through the sacrifice of their life. Normally martyrdom involves a demand for the person to give up their religious faith. When they refuse, they are tortured and eventually executed. The shedding of ones blood was regarded as a second baptism and the date of their death was celebrated as a second birthday.
Holy and Holiness in Christianity:
The concept of holiness is fundamental to all religions, though it can be an ambiguous term and difficult to define. It is an essential feature of whatever is thought to be divine and is opposed to the mundane character the world. It has acquired an ethical aspect, where ethical acts are believed to make one more holy and unethical acts make one less holy. Thus, holiness is not just a characteristic which one either does or does not have, but may be a state which one can strive to achieve.
Roman Catholicism & Saints:
The label saint is used in a special sense in the Roman Catholic Church for those people believed to have entered Gods presence in heaven and thus can provide special benefits to humanity when petitioners pray to them. Technically, they share in the Beatific Vision, which is a face-to-face experience of the presence of God. The nature of the holiness of saints varies, and it is argued that there are more saints than on the official canonical list.
Feast of All Saints:
The Feast of All Saints is celebrated on All Saints Day, November 1st in the Western Christian calendar. The purpose of this feast and celebration is to emphasize a bond between those already with God and those who remain here. Not all Christian communities had a local martyr, which was a detriment, so these churches celebrated a feast for martyrs generally. Around the 5th century, a celebration for All Saints was established; in the 8th century, Pope Gregory IV fixed the date to November 1.
Venerable Status & Saints:
The first step toward canonization and sainthood is not beatification, as many believe, but the status of venerable. When a person receives the title Venerable, it means that they are now under serious investigation to see if their holiness is sufficient to later merit beatification and canonization. It means that they have led a virtuous life certainly more virtuous than the average believer, but perhaps not quite so virtuous as that of a saint.
Beatification & Saints:
Beatification, the second step towards canonization which permits people to publicly venerate a person (from the Latin beatus, blessed and facere, to make or do) is a formal papal declaration that a deceased person deserves to be called blessed. Beatification occurs when a person had an especially holy character and (preferably) suffered a heroic death. A blessed person is assumed to be enjoying heaven, and perhaps also have special status there.
Canonization & Saints:
Canonization is the process by which a person is declared to be a saint in Roman Catholicism. Canonization occurs only after beatification and means that a person is definitely in heaven, enjoying the presence of God. Canonization permits the entire church to venerate the person and seek intercession from them. Canonization involves a ceremony, the issuance of a papal bull, and setting a feast day. Shrines may be dedicated to them and they may be declared the patron saint of some place.
Intercession of Saints:
When they act on behalf of humanity, it is called intercession. People who pray to a saint for intercession dont believe that healing, forgiveness, or various blessings come from the saint. Instead, they come from God but on account of the saints help. In this way, veneration of saints is essentially also a form of worship of God because the holiness and power of saints can only come through God.
Protestant Christianity & Saints:
In Protestant Christianity, the term saint is often used to refer to all believers. Paul himself used the term saint in this fashion in 2 Corinthians 13:12 and Ephesians 1:1. Protestant reformers explicitly rejected the lists of canonized saints to be venerated because they believe that such veneration distracted Christians from the worship of God directly.

