Actually, while an angel is in mortal form on earth, they can be affected by one thing: qeres. The Egyptians had a perfume called qeres that was used during mummification to provide the first 'sweet breathe' of the afterlife. Qeres is extremely rare substance because its recipe has been lost, but small amounts still exsist. this perfume is a lethal poison to an angel (fallen or otherwise), and if poured over, say, the blade of a knife, could in fact terminate an angel. While non-lethal to humans, it can burn or poison anyone who carries the Nephilitic gene. (see Genesis 6). If you are still thinking that all Nephilim died in the flood, think about Goliath, or King David's "men of great reknown". But yes, qeres can kill an angel. And no afterlife awaits them either. This isn't some role-playing B.S. or T.V. show, this is legit. Go ask your local Catholic priest if he knows what the 'Hashilim project' is, or the real reason Jews (who are the most dominant carriers of the Nephilitic gene) were exterminated. Or why most children born with synaethesia carry the gene. Or why Mengele expirimented on Hebrew twins. You may not get answers, but you will be asking the right questions...

I think the original answerer misunderstood the question, or just rather ran off on an tangent unrelated. Killing an Angel is really something that I would not recommend unless you want the wrath of God unleashed on you. The rest of the original answers, well, have fun with that.

the wrath of god is a joke Christians say to make them feel important and better than everyone else and also I'd like to remind everyone that a god has special rules that prevents them from harming a full human

I think much of the above is well-intentioned junk. One guy feels that a magic potion will certainly kill angels but is harmless to humans, though no one has done it or no evidence is supplied. Another guy thinks gods have rules about killing humans. What about the Great Flood, the Egyptian plagues, the Egyptrian Army pursuing the Israelites, or Sodom & Gomorrah? Rules, indeed!

Saint Michael the Archangel is referenced in the Old Testament and has been part of Christian teachings since the earliest times. In Catholic writings and traditions he acts as the defender of the Church, and chief opponent of Satan; and assists souls at the hour of death.

A widely used "Prayer to Saint Michael" was brought into official use by Pope Leo XIII in 1886 and was recommended by Pope John Paul II in 1994. The feast day of the archangels Michael, Gabriel, and Raphael is September 29.

Michael is mentioned by name five times in the Bible

-Daniel 10:13, Gabriel says, "...but the prince of the kingdom of Persia stood in my way for twenty-one days, until finally Michael, one of the chief princes, came to help me."

-Daniel 10:21, "No one supports me against all these except Michael, your prince, standing as a reinforcement and a bulwark for me"

-Daniel 12:1, "At that time there shall arise Michael, the great prince, guardian of your people; It shall be a time unsurpassed in distress since nations began until that time."

J-ude 1:9, "Yet the archangel Michael, when he argued with the devil in a dispute over the body of Moses, did not venture to pronounce a reviling judgment upon him but said, 'May the Lord rebuke you!'"

-Revelation 12:7-9, "Then war broke out in heaven; Michael and his angels battled against the dragon. The dragon and its angels fought back, but they did not prevail and there was no longer any place for them in heaven. The huge dragon, the ancient serpent, who is called the Devil and Satan, who deceived the whole world, was thrown down to earth, and its angels were thrown down with it."

In Roman Catholicism Saint Michael has four distinct roles. First, he is the Enemy of Satan and the fallen angels. He defeated Satan and ejected him from Paradise and will achieve victory at the hour of the final battle with Satan. Secondly, he is the Christian angel of death: at the hour of death, Saint Michael descends and gives each soul the chance to redeem itself before passing. Saint Michael's third role is weighing souls (hence the saint is often depicted holding scales) on Judgment Day. And finally, Saint Michael is the Guardian of the Church.

Defeat of Satan and the fallen angels

Saint Michael is viewed as the commander of the Army of God. From the time of the apostles, he has been invoked and honored as the protector of the Church. Scripture describes him as "one of the chief princes" and the leader of heaven's forces in their triumph over the powers of hell.[8]

Saint Michael defeats Satan twice, first when he ejects Satan from Paradise, and then in the final battle of the end times when the Antichrist will be defeated by him. Noted hagiographer Alban Butler, defined the role of Saint Michael:"Who is like God?" was the cry of Archangel Michael when he smote the rebel Lucifer in the conflict of the heavenly hosts. And when Antichrist shall have set up his kingdom on earth, it is St Michael who will unfurl once more the standard of the cross, sound the last trumpet, bind together the false prophet and the beast and hurl them for all eternity into the burning pool.

Saint Michael is the traditional prototype of the spiritual warrior, a paradigm extended to other warrior saints. This conflict against evil may at times be viewed as an interior battle. The concept of the warrior saint has extended to other Catholic saints, beginning with examples such as Saint George and Saint Theodore of Amasea.

At the hour of death

Saint Michael is one of the angels presumed present at the hour of death. Traditionally, he is charged to assist the dying and accompany their souls to their particular judgment, where he serves as an advocate. Cemetery chapels are often dedicated to him, where masses are offered in his honor on behalf of the departed.

Weighing souls on Judgment Day

In Catholic tradition, on Judgment Day Saint Michael weighs souls based on their deeds during their life on earth. Saint Michael is often portrayed in art with scales. This role of Saint Michael was depicted by Michelangelo on the ceiling of the Sistine Chapel. In this depiction, angels hold up two books: the smaller book held by Saint Michael records the names of the blessed, while the larger book is a list of the damned.

Guardian of the Church

The tradition of Michael as prince-protector of the Jewish people was adopted by the Christian Church. Saint Michael has long been recognized as the protector and guardian of the Church itself and the angel of the Blessed Sacrament. In a 2007 address Pope Benedict XVI urged the bishops he was ordaining to take Michael as a model in making room in the world for God, countering denials of him and thus defending man's greatness, and in acting as "true guardian angels" of the Church. Saint Michael is also the guardian angel of the Pope and has been invoked as the patron and guardian angel of many countries as well as specific professions.

Cultus

"Of all the angels, Michael was by far the most important in the Middle Ages." The earliest indications of a cult of St. Michael occur in the ancient Near East. The emperor Constantine built the Michaelion at Chalcedon on the site of an earlier temple. Other sanctuaries were located at healing springs in Anatolia, Antioch, and Egypt. Identification of St Michael with the gift of healing can be seen in Gregory the Great leading a devotional procession in 590 when the city of Rome was afflicted with a plague that killed his predecessor. Gregory reportedly saw a vision of Saint Michael atop the Mausoleum of Hadrian. The archangel sheathed his sword, suggesting to the pope that the peril was ended. He subsequently renamed the Mausoleum Castel Sant'Angelo (Castle of the Holy Angel) in honor of St. Michael.

The Visio Sancti Pauli, written in the late fourth or early fifth century, presents St Michael as an advocate for sinners, guarantor of rain, and thus a patron of agriculture. The Greek, Syrian and Coptic Churches had venerated St. Michael since at least the early sixth century. The cult of St. Michael was widespread in the British Isles during the Middle Ages.

Legends include a number of reported appearances of Saint Michael, where sanctuaries or churches were later built or dedicated to him. These include Monte Gargano in Italy early in the 6th century, where the Sanctuary of Monte Sant'Angelo, the oldest shrine in Western Europe is dedicated to Saint Michael. Early in the 8th century, Saint Michael reportedly appeared three times to Saint Aubert, the bishop of Avranches in Normandy, France and instructed him to build a church on the small island now known as Mont Saint-Michel. Several healings were reported when the church was being built and Mont Saint-Michel still remains a Catholic pilgrimage site.

The role of Saint Michael as protector and guardian has also led to the design of statues that depict him and the construction of Churches and monasteries at specific locations. Because most monastic islands lie close to land, they were viewed as forts holding demons at a distance against attacks on the Church. Monasteries such as Mont Saint-Michel off the coast of Normandy, France and Skellig Michael, off the coast of County Kerry, Ireland, dedicated to the Archangel are examples of these. Another notable structure is that of St Michael's Mount, located in Mounts Bay, near Penzance, Cornwall - a stunning island castle that resembles Mont Saint-Michel, and can only be reached on foot at low tide.

St. Bernard of Clairvaux recommended the invocation of Saint Michael at the time of temptation and sorrow: "Whenever any grievous temptation or vehement sorrow oppresses thee, invoke thy guardian, thy leader, cry out to him, and say, 'Lord, save us, lest we perish!'"

St. Francis of Assisi was specially devoted to Saint Michael and would fast for about forty days from the feast of the Assumption (August 15) to Saint Michael's feast day on September 29. Some Franciscan communities continue to observe the period from August 15 to September 29 as "St. Michael's Lent", a time of fasting and prayer.

from A Catholic Dictionary, edited by Donald Attwater, Second edition, revised 1957

The Council of Trent

The 19th ecumenical council held at Trent in the Austrian Tyrol, 1545-63, summoned for the purpose of combating Protestantism and reforming the discipline of the Church; the longest and one of the most important of all general councils. It dealt in detail with the doctrinal innovations of the Reformers and with those gross abuses which gave them an opportunity to take root. It was one of the most important events of modern history and has had lasting effect. The principal dogmatic decisions were: the confirmation of the Nicene creed; the authenticity of the Latin Vulgate and the canonicity of all books contained therein and of them only; the definition of the doctrine of Original Sin; the precision of the doctrine of Justification, condemning justification by faith alone and imputation of grace; the condemnation of thirty errors about the sacraments; the definition of the Real Presence and of Transubstantiation as its mode: the precision of the doctrine of the sacraments of penance and Extreme Unction; the declaration that holy communion in both kinds was not necessary for lay-people and clerics not celebrating, Christ being received whole and entire under either species; the precision of doctrine concerning the sacrifice of the Mass and the sacraments of holy Orders and Matrimony; the affirmation of the doctrines of Purgatory, of the invocation of saints, and the veneration of them, their relics and images, and of Indulgences. Far-reaching decrees of reformation in discipline and morals were adopted involving many alterations in canon law, e.g. the decree Tametsi.

The four decrees were:

1. provide for more clerical discipline

2. remove church abuses

3. reaffirm the sacraments

4. provide a system for education clergy

It was a Council held in Trent in the 15th and 16th centuries in response to the Reformation. One of the main outcomes was the establishment of the seminary system. This moved theology away from the university to a separate system for priests to train. As this happened, the teaching of moral theology became better improved. This led to more people going to confession, which led to a higher demand for priests, which increased the number of priests in seminaries. I'm sure that there are more results, but that's the one that I know about.

had previously been decided.

He didn't 'fall'. The Bible says he was thrown out... "Hurled to the earth"(Revelation 12:9-12)...and his actual name is unknown to us, because he's not worthy of being remembered.

His descriptive titles, however, are 'satan' (which means opposer ) and 'devil' (which means slanderer). These labels were given to him because of his taking a course of opposition and resistance to God.

The most important reason is of course that Muslims actually believe in angels. Another important reason is that the angel Gabriel (Jibrail) is believed to have revealed the Koran (Quran) to Muhammad. This story means that Islam actually depends on the existence of angels.

The Hebrew word translated into English as 'Angel' first appear in Jewish scripture written during and after the Babylonian Exile, as messengers of God. A similar concept had already existed in the Zoroastrian religion of the Persians.

Our word 'angel' comes from the Greek word for messenger, angelos.