Today, our idea of heavenly angels evolved from several religions, but has been strongly influenced in Western cultures primarily by traditional Christianity.
Heavenly angels within Christianity's teachings can play several roles within the realm of heaven.
A single heaven is the Christian idea of a final resting place after death, while Islam, Jewish mysticism and Christian Gnosticism teaches the existence of multiple heavens (usually seven), which are levels having angels found within them. These heavenly levels differ and may represent varying degrees of bliss (to no bliss) depending on the religion itself.
The Christian idea of heavenly angels are that of messengers and guardians that interact with mankind from the heavenly realm. However, there are also descriptions of what are believed to be other types of angels that surround the court and throne of God, such as Cherubim (Ezekiel 10) and Seraphim (Isaiah 6). These heavenly angels find their roots in the Hebrew Bible, but are also thought to be more symbolic in interpretation and not the same as the messenger angels which are believed to interact with mankind. In other words, some see these angels as caretakers of God, while others see them as representing attributes and truths about the relationship between God and mankind. Those are two different interpretations altogether.
In biblical passages, heavenly angels often are described as having human form, being sent forth to warn or enlighten; though at times they are described as being mighty in duty. The messengers (they are called angels in Genesis 19:1) that visited Lot, for example, are described as being men by those who observed them from the city of Sodom (Genesis 19:5). The images of angels with wings and halos we know today were depictions from artists after the fourth century. Angels preceding that time in Christianity were painted without wings and halos, appearing as men. There were of course similar, earlier ideas of angel-like deities found within the religions of other cultures. Some of these cultures simply influenced the work of Christian artists. (See Angels in Early Christian Art)
There are many views concerning heavenly angels and their roles. In just one example, the mystical Hebrew book, 3 Enoch, gives the names of each angel prince of the seven heavens, where we find out that each angelic prince is ministered to by an astounding 496,000 heavenly angels!
We are of the opinion at Angels & Ghosts that angels have been misunderstood. Heavenly angels are likely just messengers in spirit that bring forth truths and guidance to others. A messenger could simply be an enlightened human spirit on another plane of existence (call it from a heavenly, or higher realm) who communicates with those of us in the earthly plane. My writing of this article makes me a messenger to the reader - an example of how broad the meaning of the term messenger can be applied.
Yet, there is another idea for certain angelic visitations from the heavenly realm to consider. My friend Laura Lyn suggests that some heavenly angels may be simply the collective human consciousness manifesting as different loving attributes that we need to receive into our heavens...our higher place of understanding. After all, we are all connected and one Spirit, right?
For more information on heavenly angels, read: History of Angels