This information is gained from a closer reading of "Lord of the Rings" (it's not clear from the movie), and from other writings of Tolkein.
For a definitive discussion, see the book "The Tolkien Companion" (a book which discusses various characters, places, and things from Tolkien's works). Look up "Wizards" and learn truth of what Tolkien meant them to be.
As I am sure you are aware, the background (previous 9000 years of history) of LOTR is told in The Silmarillon. It reads a lot like the Appendices to LOTR. From your remarks, I take it that you haven't read it lately.
Obviously, not from the Christian God, but then it really wouldn't be as much a fanstasy if it used a real world God.
In some ways, Tolkien's mythology parallels the Old Testament. The "genesis" of his mythology involves the rebellion of an archangel (for want of a better term) who believes that he should have the power to create life and be equal to the one God. The Silmarillion, chronologically the first book, is about a war waged by this fallen archangel against the rest of the world. The parallel to the fall of Lucifer is obvious. And as with Satan, the fatal flaw of this archangel is hubris
The Lord of the Rings tells the story of a later time, where a fallen angel who served the archangel tries to dominate the world as well. The wizards are not human at all, but rather good angels who were sent to help the rest of the world against this fallen angel. Though Tolkien doesn't use the terms angel and archangel, the connection between those concepts and the way he describes his beings are clear.
The tone of the LOTR, as others have pointed out, is very Christian. The hero hobbit Frodo basically sacrifices himself to protect the world from a greater evil, and his greatest strength is his moral courage and humility. It is a profoundly moral story, and the morality it teaches is a good one. In fact, many people who don't like LOTR blast it for its obvious Christian overtones, and view it as propaganda for Christianity.
Wizards were angelic beings sent from God in LOTR? Get a grip, I don't remember a single word about Christianity or God(the one we worship) in either the books or the movie. Sounds like a unique interpretation to me.
You were not paying attention, then. It is made quite clear in the books, especially, that the Istari, the five wizards who make up Gandalf's order, were sent into middle earth by "God" (Eru, the One, the creator, as detailed in The Simarillion) in order to help those in middle earth fight against Sauron and other evils. The two blue wizards are off in the east doing something which does not come into any of the stories which Tolkien wrote; Radagast the Brown is only concerned with trees and birds and other creatures, and spends most of his time in and around Mirkwood, and does not get involved much with the larger doings of the world which Gandalf and Saruman are concerned with; Radagast is good but his area of expertise does not bring him much into the stories, except for a brief mention in The Hobbit, and the small role he played in The Fellowship of the Ring (which got cut out of the movie version). Saruman the White is the head of the council, and becomes evil after being corrupted by desire for the kind of power which Sauron has. Gandalf the Grey....well, read for The Two Towers or wait for the movie.
The wizards are "angels" in the sense that they are sent by God to help lesser beings who are lost, far from God's help, in an existence cut off from direct access to the higher realms. To many people think of angels as invisible entities which are up in heaven with God; the original notion of angels was that they were beings who appeared as ordinary mortals but who were more than they seemed and who were sent for a purpose by a higher power (God), whether as messengers, or to perform some other function. That's why Gandalf and the others are not "wizards" in the sense of being mortal men who dabble in magic, but are in fact immortal beings disguised as mortal "wizards"; they are not omnipotent but are very powerful compared to ordinary mortals.
Of course Tolkien doesn't mention Christianity, because he was writing a myth of something that was supposed to have happened thousands of years before recorded history, and therefore something that predated Christianity and all other known religions. But quite clearly, the creator God in his myth is the same God of Christianity, only that the appearance of Christ, in the fullness of time, is something which will not happen until many, many thousands of years after his stories take place, when they and everything in them are long forgotten. Hence the Christian background to stories which are not otherwise explicitly Christian.
The cosmology of Tolkien is EXTREEMLY Christian. Eru was The One God...the Valar were his Arch-Angels, Melkor was the fallen Arch-Angel that created evil and fought against the rest. Wizards were under the employ of the 'good' Arch-Angels. The Balrogs were Melkor’s equivalent agents….