From "Manual of Muad'Dib" by the Princess Irulan

Muad'Dib: "Religion often partakes of the myth of progress that shields us from the terrors of an uncertain future."
C.E.T. Commentaries: Identical wording. (The Azhar Book traces this statement to the first century religious writer, Neshou; through a paraphrase.)
Muad'Dib: "If a child, an untrained person, an ignorant person, or an insane person incites trouble, it is the fault of authority for not predicting and preventing that trouble. "
O.C. Bible: "Any sin can be ascribed, at least in part, to a natural bad tendency that is an extenuating circumstance acceptable to God." (The Azhar Book traces this to the ancient Semitic Tawra.)
Muad'Dib: "Reach forth thy hand and eat what God has provided thee; and when thou are replenished, praise the Lord."
O.C. Bible: a paraphrase with identical meaning. (The Azhar Book traces this in slightly different form to First Islam.)
Muad'Dib: "Kindness is the beginning of cruelty."
Fremen Kitab al-Ibar: "The weight of a kindly God is a fearful thing. Did not God give us the burning sun (Al-Lat)? Did not God give us the Mothers of Moisture (Reverend Mothers)? Did not God give us Shaitan (Iblis, Satan)? From Shaitan did we not get the hurtfulness of speed?"
(This is the source of the Fremen saying: "Speed comes from Shaitan." Consider: for every one hundred calories of heat generated by exercise [speed] the body evaporates about six ounces of perspiration. The Fremen word for perspiration is bakka or tears and, in one pronunciation, translates: "The life essence that Shaitan squeezes from your soul.")
Muad'Dib's arrival is called "religiously timely" by Koneywell, but timing had little to do with it. As Muad'Dib himself said: "I am here; so . . . "
It is, however, vital to an understanding of Muad'Dib's religious impact that you never lose sight of one fact: the Fremen were a desert people whose entire ancestry was accustomed to hostile landscapes. Mysticism isn't difficult when you survive each second by surmounting open hostility. "You are there—so . . . "
With such a tradition, suffering is accepted—perhaps as unconscious punishment, but accepted. And it's well to note that Fremen ritual gives almost complete freedom from guilt feelings. This isn't necessarily because their law and religion were identical, making disobedience a sin. It's likely closer to the mark to say they cleansed themselves of guilt easily because their everyday existence required brutal judgments (often deadly) which in a softer land would burden men with unbearable guilt.
This is likely one of the roots of Fremen emphasis on superstition (disregarding the Missionaria Protectiva's ministrations). What matter that whistling sands are an omen? What matter that you must make the sign of the fist when first you see First Moon? A man's flesh is his own and his water belongs to the tribe—and the mystery of life isn't a problem to solve but a reality to experience. Omens help you remember this. And because you are here , because you have the religion, victory cannot evade you in the end.
As the Bene Gesserit taught for centuries, long before they ran afoul of the Fremen: "When religion and politics ride the same cart, when that cart is driven by a living holy man (baraka), nothing can stand in their path."

Appendix III: Report on Bene Gesserit