The worship of reason is arrogance and betrays a lack of intelligence. The rejection of reason is cowardice and betrays a lack of faith.

Generally speaking, the errors in religion are dangerous; those in philosophy only ridiculous.

Nothing can be more contrary to religion and the clergy than reason and common sense.

Such people as can be prevailed upon to believe, that their reason is depraved, may easily be led by the nose, and duped into superstition at the pleasure of those in whom they confide, and there remain from generation to generation: for when they throw by the law of reason the only one which God gave them to direct them in their speculations and duty, they are exposed to ignorant or insidious teachers, and also to their own irregular passions, and to the folly and enthusiasm of those about them, which nothing but reason can prevent or restrain...

I have argued that religion is to science as superstition is to reason; indeed, that is the very reason they are incompatible.

Those who invalidate reason, ought seriously to consider, 'whether they argue against reason, with or without reason; if with reason, then they establish the principle, that they are laboring to dethrone;' but if they argue without reason, (which, in order to be consistent with themselves, they must do,) they are out of the reach of rational conviction, nor do they deserve a rational argument.

Although the far territory of the extreme can exert an intoxicating pull on susceptible individuals of all bents, extremism seems to be especially prevalent among those inclined by temperament or upbringing toward religious pursuits. Faith is the very antithesis of reason, injudiciousness a crucial component of spiritual devotion. And when religious fanaticism supplants ratiocination, all bets are suddenly off.

We must respect our own dignity as rational beings and thus diminish the power of fraud. It is better to be free than be a slave, better to know than to be ignorant. It is reason that helps us to reject what is falsely taught and believed about God, that He is a detective officer or a capricious despot or a glorified schoolmaster. It is essential that we should subject religious beliefs to the scrutiny of reason.

Those who invalidate reason ought seriously to consider whether they argue against reason with or without reason; if with reason, then they establish the principle that they are laboring to dethrone: but if they argue without reason (which, in order to be consistent with themselves they must do), they are out of reach of rational conviction, nor do they deserve a rational argument.

On religion, many are destined to reason wrongly; others not to reason at all; and others to persecute those who do reason.

The weak spot of religion is its ridiculousness

To be truly rational we need to acknowledge the limits of our rationality: nothing is more irrational than an unwarranted faith in reason.

No doctrine can be a proper object of our faith which it is not more reasonable to believe than to reject. […] In receiving therefore the most mysterious doctrines of revelation, the ultimate appeal is to reason: not to determine whether she could have discovered these truths; not to declare whether considered in themselves they appear probable; but to decide whether it is not more reasonable to believe what God speaks, than to confide in our own crude and feeble conceptions.

[W]e have more than two options... a critique of reason does not have to be a call for the return of superstition and arbitrary power.... [O]ur problems do not lie with reason itself but with our obsessive treatment of reason as an absolute value. Certainly it is one of our qualities, but it functions positively only when balanced and limited by the others.