“I conceive of nothing, in religion, science, or philosophy, that is more than the proper thing to wear, for a while.”

Answer from Pasteur to his disciple Elie Metchnikoff when was questioned whether his approach to spontaneous generation was bound to a religious ideal. According to Patrice Debré's Luis Pasteur, 2000 https://books.google.co.uk/books?id=RzOcl-FLw30C&lpg=PP1&pg=PA176#v=onepage&q&f=false,, p. 176.
Disputed

Source: Green Mars (1993), Chapter 8, “Social Engineering” (p. 401)

Foreword
Logical Syntax of Language, 1934/1937

The trial of Charles B. Reynolds for blasphemy (1887)
Context: I want you to understand what has been done in the world to force men to think alike. It seems to me that if there is some infinite being who wants us to think alike he would have made us alike. Why did he not do so? Why did he make your brain so that you could not by any possibility be a Methodist? Why did he make yours so that you could not be a Catholic? And why did he make the brain of another so that he is an unbeliever — why the brain of another so that he became a Mohammedan — if he wanted us all to believe alike?
After all, maybe Nature is good enough and grand enough and broad enough to give us the diversity born of liberty. Maybe, after all, it would not be best for us all to be just the same. What a stupid world, if everybody said yes to everything that everybody else might say.
The most important thing in this world is liberty. More important than food or clothes — more important than gold or houses or lands — more important than art or science — more important than all religions, is the liberty of man.

Introduction
A Treatise of Human Nature (1739-40)
Context: Nothing is more usual and more natural for those, who pretend to discover anything new to the world in philosophy and the sciences, than to insinuate the praises of their own systems, by decrying all those, which have been advanced before them. And indeed were they content with lamenting that ignorance, which we still lie under in the most important questions, that can come before the tribunal of human reason, there are few, who have an acquaintance with the sciences, that would not readily agree with them. 'Tis easy for one of judgment and learning, to perceive the weak foundation even of those systems, which have obtained the greatest credit, and have carried their pretensions highest to accurate and profound reasoning. Principles taken upon trust, consequences lamely deduced from them, want of coherence in the parts, and of evidence in the whole, these are every where to be met with in the systems of the most eminent philosophers, and seem to have drawn disgrace upon philosophy itself.

Source: Life, the Truth, and Being Free (2010), p. 154

Life Without Principle (1863)

Autobiography (1936; 1949; 1958)
Context: Organised religion allying itself to theology and often more concerned with its vested interests than with the things of the spirit encourages a temper which is the very opposite of science. It produces narrowness and intolerance, credulity and superstition, emotionalism and irrationalism. It tends to close and limit the mind of man and to produce a temper of a dependent, unfree person.
Even if God did not exist, it would be necessary to invent Him, so Voltaire, said … perhaps that is true, and indeed the mind of man has always been trying to fashion some such mental image or conception which grew with the mind's growth. But there is something also in the reverse proposition: even if God exist, it may be desirable not to look up to Him or to rely upon Him. Too much dependence on supernatural forces may lead, and has often led, to loss of self-reliance in man, and to a blunting of his capacity and creative ability. And yet some faith seems necessary in things of the spirit which are beyond the scope of our physical world, some reliance on moral, spiritual, and idealistic conceptions, or else we have no anchorage, no objectives or purpose in life. Whether we believe in God or not, it is impossible not to believe in something, whether we call it a creative life-giving force, or vital energy inherent in matter which gives it its capacity for self-movement and change and growth, or by some other name, something that is as real, though elusive, as life is real when contrasted with death. <!-- p. 524 (1946)