The most important forces of the astral body are those of faith.

Rudolf Steiner:

Many of those who, on account of their so-called scientific world-conception, have become arrogant and overbearing, now say: “The ages of faith are long past; they were fit for mankind in their stage of childhood, but men have now progressed to knowledge. Today people must have knowledge of everything and should no longer merely believe.” Now that may sound all very well, but it does not rest on genuine understanding. We must ask more questions about such matters than merely whether in the present course of human evolution knowledge has been gained through ordinary science. These other questions must be put: Does faith, as such, mean anything for mankind? May it not be part of a man's very nature to believe?

Naturally, it might be quite possible that people should want, for some reason, to dispense with faith, to throw it over. But just as a man is allowed for a time to play fast and loose with his health without any obvious harm, it might very well be — and is actually so — that people come to look upon faith merely as a cherished gift to their fathers in the past, which is just as if for a time they were recklessly to abuse their health, thereby using up the forces they once possessed. When a man looks upon faith in that way, however, he is still — where the life-forces of his soul are concerned — living on the old gift of faith handed down to him through tradition. It is not for man to decide whether to lay aside faith or not; faith is a question of life-giving forces in his soul. The important point is not whether we believe or not, but that the forces expressed in the word ‘faith’ are necessary to the soul. For the soul incapable of faith becomes withered, dried-up as the desert.

There were once men who, without any knowledge of natural science, were much cleverer than those today with a scientific world-conception. They did not say what people imagine they would have said: “I believe what I do not know.” They said: “I believe what I know for certain.” Knowledge is the only foundation of faith. We should know in order to take increasing possession of those forces which are forces of faith in the human soul. In our soul we must have what enables us to look toward a supersensible world, makes it possible for us to turn all our thoughts and conceptions in that direction.

If we do not possess forces such as are expressed in the word ‘faith’, something in us goes to waste; we wither as do the leaves in autumn. For a while this may not seem to matter — then things begin to go wrong. Were men in reality to lose all faith, they would soon see what it means for evolution. By losing the forces of faith they would be incapacitated for finding their way about in life; their very existence would be undermined by fear, care, and anxiety. To put it briefly, it is through the forces of faith alone that we can receive the life which should well up to invigorate the soul.

This is because, imperceptible at first for ordinary consciousness, there lies in the hidden depths of our being something in which our true ego is embedded. This something, which immediately makes itself felt if we fail to bring it fresh life, is the human sheath where the forces of faith are active. We may term it the faith-soul, or — as I prefer — the faith-body. It has hitherto been given the more abstract name of astral body. The most important forces of the astral body are those of faith, so the term astral body and the term faith-body are equally justified.

Source: https://martyrion.blogspot.com/2020/12/faith-our-astral-body-love-our-etheric.html