Belief and doubt are living attitudes, and involve conduct on our part. Our only way, for example, of doubting, or refusing to believe, that a certain thing is, is continuing to act as if it were not.

To believe is to know that one believes, and to know that one believes is no longer to believe.

To believe is to know you believe, and to know you believe is not to believe.

You believe someone not because you have no doubts about them. Belief is not the absence of doubt. You believe someone because you don’t have enough doubts about them.

Belief is in ignorance. If you know, you know. And it is good that if you don’t know, know that you don’t know — the belief can deceive you. The belief can create an atmosphere in your mind, where, without knowing, you start thinking that you know. Belief is not trust, and the more strongly you say that you believe totally, the more you are afraid of the doubt within you.

Belief, that sacred faculty which prompts the decisions of our will, and knits into harmonious working all the compacted energies of our being, is ours not for ourselves but for humanity. It is rightly used on truths which have been established by long experience and waiting toil, and which have stood in the fierce light of free and fearless questioning. Then it helps to bind men together, and to strengthen and direct their common action. It is desecrated when given to unproved and unquestioned statements, for the solace and private pleasure of the believer; to add a tinsel splendour to the plain straight road of our life and display a bright mirage beyond it; or even to drown the common sorrows of our kind by a self-deception which allows them not only to cast down, but also to degrade us. Whoso would deserve well of his fellows in this matter will guard the purity of his beliefs with a very fanaticism of jealous care, lest at any time it should rest on an unworthy object, and catch a stain which can never be wiped away. It is not only the leader of men, statesmen, philosopher, or poet, that owes this bounden duty to mankind. Every rustic who delivers in the village alehouse his slow, infrequent sentences, may help to kill or keep alive the fatal superstitions which clog his race. Every hard-worked wife of an artisan may transmit to her children beliefs which shall knit society together, or rend it in pieces. No simplicity of mind, no obscurity of station, can escape the universal duty of questioning all that we believe. It is true that this duty is a hard one, and the doubt which comes out of it is often a very bitter thing. It leaves us bare and powerless where we thought that we were safe and strong. To know all about anything is to know how to deal with it under all circumstances. We feel much happier and more secure when we think we know precisely what to do, no matter what happens, than when we have lost our way and do not know where to turn. And if we have supposed ourselves to know all about anything, and to be capable of doing what is fit in regard to it, we naturally do not like to find that we are really ignorant and powerless, that we have to begin again at the beginning, and try to learn what the thing is and how it is to be dealt with — if indeed anything can be learnt about it. It is the sense of power attached to a sense of knowledge that makes men desirous of believing, and afraid of doubting.

It is always easier to believe than to deny. Our minds are naturally affirmative; it is not till the second or third thought that doubt begins. Belief is so vital and necessary that one would say the tendency was made strong at the perpetual risk of extra belief and superstition; it were better to believe too much than not enough. Hence mankind have always believed too much, as if to make sure that the anchor hold. To believe just enough, to free his mind from all cant and from all illusion, and see things just as in themselves they are, is the aim of the philosopher or of the true skeptic.

Doubt is the beginning of wisdom. It means caution, independence, honesty and veracity. Faith means negligence, serfdom, insincerity and deception. The man who never doubts never thinks. He is like a straw in the wind or a waif on the sea. He is one of the helpless, docile, unquestioning millions, who keep the world in a state of stagnation, and serve as a fulcrum for the lever of despotism. The stupidity of the people, says Whitman, is always inviting the insolence of power.

I believe” means “I trust”. No more must I dream of trusting in myself, I no longer need to justify myself, to excuse myself, to attempt to save and preserve myself. This most profound effort of man to trust to himself, to see himself as in the right, has become pointless. I believe — not in myself — I believe in God the Father, the Son and the Holy Ghost. So also trust in any sort of authorities, who might offer themselves to me as trustworthy, as an anchor which I ought to hold on to, has become frail and superfluous.

Belief consists in accepting the affirmations of the soul; unbelief, in denying them.

Belief means not wanting to know what is true.

Those who believe, believe everything, while those who doubt don't believe a thing.

Every mental act is composed of doubt and belief,
but it is belief that is the positive, it is belief
that sustains thought and holds the world together.

Doubt is a lack of confidence or assurance that God will keep his promises. Faith is an active confidence that God’s promises are always true.