Angels are messengers of God in the Hebrew and Christian Bibles along with the Quran. The English word angel is derived from the Greek ἄγγελος, a translation of מלאך (mal'akh) in the Hebrew Bible (Tanakh); a similar term, ملائكة (Malāīkah), is used in the Qur'an. The Hebrew and Greek words originally mean messenger, and depending on the context may refer either to a human messenger (possibly a prophet or priest, such as Malachi, "my messenger", but also for more mundane characters, as in the Greek superscription that the Book of Malachi was written "by the hand of his messenger" (ἀγγήλου)) or to a supernatural messenger, such as the "Mal'akh YHWH," who (depending on interpretation) is either a messenger from God, an aspect of God (such as the Logos), or God Himself as the messenger (the "theophanic angel.")
The term "angel" has also been expanded to various notions of spiritual beings found in many other religious traditions.
Other roles of angels include protecting and guiding human beings, and carrying out God's tasks.
The theological study of angels is known as angelology. In art, angels are often depicted with wings; perhaps reflecting the descriptions in Revelation 4:6-8 -- of the Four Living Creatures (τὰ τέσσαρα ζῷα) and the descriptions in the Hebrew Bible -- of cherubim and seraphim (the chayot in Ezekiel's Merkabah vision and the Seraphim of Isaiah). However, while cherubim and seraphim have wings in the Bible, no angel is mentioned as having wings.
The word angel in English is a fusion of the Old English word engel (with a hard g) and the Old French angele. Both derive from the Latin angelus which in turn is the romanization of the ancient Greek ἄγγελος (angelos), "messenger", which is related to the Greek verb ἀγγέλλω (angellō), meaning "bear a message, announce, bring news of" etc. The earliest form of the word is the Mycenaean a-ke-ro attested in Linear B syllabic script.
Philosophically, angels are "pure contingent spirits." According to Aristotle, just as there is a First Mover, so, too, must there be spiritual secondary movers.[Need quotation to verify] Thomas Aquinas (13th century) expands upon this in his Summa contra Gentiles and Summa Theologica.
The Bible uses the terms מלאך אלהים (mal'akh Elohim; messenger of God), מלאך יהוה (mal'akh YHWH; messenger of the Lord), בני אלהים (b'nai Elohim; sons of God) and הקודשים (ha-qodeshim; the holy ones) to refer to beings traditionally interpreted as angels. Later texts use other terms, such as העליונים (ha'elyoneem; the upper ones).
Scholar Michael D. Coogan notes that it is only in the late books that the terms "come to mean the benevolent semidivine beings familiar from later mythology and art." Daniel is the first biblical figure to refer to individual angels by name, mentioning Gabriel (God's primary messenger) in Daniel 9:21 and Michael (the holy fighter) in Daniel 10:13. These angels are part of Daniel's apocalyptic visions and are an important part of all apocalyptic literature. Coogan explains the development of this concept of angels: "In the postexilic period, with the development of explicit monotheism, these divine beings—the 'sons of God' who were members of the divine council—were in effect demoted to what are now known as 'angels', understood as beings created by God, but immortal and thus superior to humans." This conception of angels is best understood in contrast to demons and is often thought to be "influenced by the ancient Persian religious tradition of Zoroastrianism, which viewed the world as a battleground between forces of good and forces of evil, between light and darkness." One of these "sons of God" is "the satan", a figure depicted in among other places according to the Book of Job.
In post-Biblical Judaism, certain angels took on particular significance and developed unique personalities and roles. Though these archangels were believed to rank among the heavenly host, no systematic hierarchy ever developed. Metatron is considered one of the highest of the angels in Merkabah and Kabbalist mysticism and often serves as a scribe; he is briefly mentioned in the Talmud and figures prominently in Merkabah mystical texts. Michael, who serves as a warrior and advocate for Israel (Daniel 10:13), is looked upon particularly fondly. Gabriel is mentioned in the Book of Daniel (Daniel 8:15–17), the Book of Tobit, and briefly in the Talmud, as well as in many Merkabah mystical texts. There is no evidence in Judaism for the worship of angels, but there is evidence for the invocation and sometimes even conjuration of angels.
Medieval Jewish philosopher Maimonides explained his view of angels in his Guide for the Perplexed II:4 and II:6:
