Whenever there is a withering of the law and an uprising of lawlessness on all sides, then I manifest Myself.
For the salvation of the righteous and the destruction of such as do evil, for the firm establishing of the Law, I come to birth age after age.
– Bhagavad Gita, Book IV, Sutra 7, 8. 
Right down the ages, in many world cycles and in many countries (and today in all) great points of tension have occurred which have been characterized by a hopeful sense of expectancy. Some one is expected and His coming is anticipated. Always in the past, it has been the religious teachers of the period who have fostered and proclaimed this expectancy and the time has always been one of chaos and difficulty, of a climaxing point at the close of a civilization or culture and when the resources of the old religions have seemed inadequate to meet men’s difficulties or to solve their problems. The coming of the Avatar, the advent of a Coming One and, in terms of today, the reappearance of the Christ are the keynotes of the prevalent expectancy. When the times are ripe, the invocation of the masses is strident enough and the faith of those who know is keen enough, then always He has come and today will be no exception to this ancient rule or to this universal law. For decades, the reappearance of the Christ, the Avatar, has been anticipated by the faithful in both hemispheres – not only by the Christian faithful, but by those who look for Maitreya and for the Boddhisattva as well as those who expect the Imam Mahdi.
When men feel that they have exhausted all their own resources and have come to an end of all their own innate possibilities and that the problems and conditions confronting them are beyond their solving or handling, they are apt to look for a divine Intermediary and for the  Mediator Who will plead their cause with God and bring about a rescue. They look for a Savior. This doctrine of Mediators, of Messiahs, of Christs and of Avatars can be found running like a golden thread through all the world faiths and Scriptures and, relating these world Scriptures to some central source of emanation, they are found in rich abundance everywhere. Even the human soul is regarded as an intermediary between man and God; Christ is believed by countless millions to act as the divine mediator between humanity and divinity.
The whole system of spiritual revelation is based (and has always been based) on this doctrine of interdependence, of a planned and arranged conscious linking and of the transmission of energy from one aspect of divine manifestation to another – from God in the “secret Place of the Most High” to the humblest human being, living and struggling and sorrowing on earth. Everywhere this transmission is to be found; “I am come that they may have life” says the Christ, and the Scriptures of the world are full of the intervention of some Being, originating from some source higher than the strictly human. Always the appropriate mechanism is found through which divinity can reach and communicate with humanity, and it is with this communication and these Instruments of divine energy that the doctrine of Avatars or of divine “Coming Ones” has to do.
An Avatar is one Who has a peculiar capacity (besides a self-initiated task and a preordained destiny) to transmit energy or divine power. This is necessarily a deep mystery and was demonstrated in a peculiar manner and in relation to cosmic energy by the Christ Who – for the first time in planetary history, as far as we know – transmitted the divine energy of love directly to our planet and in a most definite sense to humanity. Always  too these Avatars or divine Messengers are linked with the concept of some subjective spiritual Order or Hierarchy of spiritual Lives, Who are concerned with the developing welfare of humanity. All we really know is that, down the ages, great and divine Representatives of God embody divine purpose, and affect the entire world in such a manner that Their names and Their influence are known and felt thousands of years after They no longer walk among men. Again and again, They have come and have left a changed world and some new world religion behind Them; we know also that prophecy and faith have ever held out to mankind the promise of Their coming again amongst us in an hour of need. These statements are statements of fact, historically proven. Beyond this we know relatively few details.
The word “Avatar” is a Sanskrit word, meaning literally “coming down from far away.” Ava (as prefix to verbs and verbal nouns) expresses the idea of “off, away, down.” Avataram, (comparative) farther away. The root AV seems at all times to denote the idea of Protection from above, and is used in compounds, in words referring to protections by kings or rulers; in regard to the gods, it means accepted favorably when a sacrifice is offered. With the result that the root word can be said to mean “Coming down with the approval of the higher source from which it came and with benefit to the place at which it arrives.” (From Monier-Williams Sanskrit Dictionary.)
All the world Avatars or Saviors, however, express two basic incentives: the need of God to contact humanity and to have relationship with men and the need of humanity for divine contact, help and understanding. Subject to those incentives, all true Avatars are therefore divine Intermediaries. They can act in this fashion because They  have completely divorced Themselves from every limitation, from all sense of selfhood and separativeness and are no longer – by ordinary human standards – the dramatic center of Their lives, as are most of us. When They have reached that stage of spiritual decentralization, They Themselves can then become events in the life of our planet; toward Them every eye can look and all men can be affected. Therefore, an Avatar or a Christ comes forth for two reasons: one, the inscrutable and unknown Cause prompts Him so to do, and the other is the demand or the invocation of humanity itself. An Avatar is consequently a spiritual event, coming to us to bring about great changes or major restorations, to inaugurate a new civilization or to restore the “ancient landmarks” and lead man nearer to the divine. They have been defined as “extraordinary men Who from time to time appear to change the face of the world and inaugurate a new era in the destinies of humanity.” They come in times of crisis; They frequently create crises in order to bring to an end the old and the undesirable and make way for new and more suitable forms for the evolving life of God Immanent in Nature. They come when evil is rampant. For this reason, if for no other, an Avatar may be looked for today. The necessary stage is set for the reappearance of the Christ.
Avatars are of all degrees and kinds; some of them are of great planetary importance because They express whole cycles of future development within Themselves and strike the note and give the teaching which will bring in a new age and a new civilization; They embody great truths towards which the masses of men must work and which still constitute an objective to the greatest minds of the age, even though as yet unrealized. Certain Avatars also express in Themselves the sumtotal, of human achievement  and of racial perfection, and thus become the “ideal men” of the ages. Others, greater still, are permitted to be the custodians of some divine principle or some divine quality which needs fresh presentation and expression upon Earth; this They can be because They have achieved perfection and have attained to the highest possible initiations. They have the gift of being these embodied spiritual qualities, and because They have in fullness expressed such a specific principle or quality They can act as channels for its transmission from the center of all spiritual Life. This is the basis for the doctrine of Avatars or Divine Messengers.
Such an one was the Christ; He was twice an Avatar because He not only struck the keynote of the new age (over two thousand years ago) but He also, in some mysterious and incomprehensible manner, embodied in Himself the divine Principle of Love; He was the first to reveal to men the true nature of God. The invocative cry of humanity (the second of the incentives producing a divine Emergence) is potent in effect because the souls of men, particularly in concerted action, have, in them something which is akin to the divine nature of the Avatar. We are all Gods, all the children of the One Father, as the latest of the Avatars, the Christ, has told us. It is that divine center in every human heart which, when awakened into activity, can call forth response from the high Place where the Coming One awaits His hour of appearance. It is only the united demand of humanity, its “massed intent,” which can precipitate the descent (as it is called) of an Avatar.
To sum up, therefore: the doctrine of Avatars is paralleled by the doctrine of the continuity of revelation. Ever down the ages, and at every great human crisis, always in the hours of necessity, at the founding of a new  race, or in the awakening of a prepared humanity to a new and wider vision, the Heart of God – impelled by the Law of Compassion – sends forth a Teacher, a world Savior, an Illuminator, an Avatar, a transmitting Intermediary, a Christ. He gives the message which will heal, which will indicate the next step to be taken by the race of men, which will illumine a dark world problem and give to man an expression of some hitherto unrealized aspect of divinity. Upon this fact of the continuity of revelation and upon the sequence of this progressive manifestation of the divine Nature, is based the doctrine of Avatars, divine Messengers, divine Appearances and Saviors. To Them all, history unmistakenly testifies. It is upon the fact of this continuity, this sequence of Messengers and Avatars, and upon the dire and dreadful need of humanity at this time, that the worldwide expectancy of the reappearance of the Christ is based. It is the innate recognition of all these facts that has led to the steadily mounting invocative cry of humanity in every land for some form of divine relief or divine intervention; it is the recognition of these facts which also prompts the order which has gone forth from “the center where the will of God is known” that the Avatar should come again; it is the knowledge of both these demands which has led the Christ to let His disciples in every land know that He will reappear when they have done the needed preparatory work.
The Reappearance of the Christ – Chapter I – The Doctrine of Avatars
Alice Bailey & Djwhal Khul