“Be not afraid! In admitting a creator, refuse not to examine his creation; and take not the assertions of creatures like yourselves, in place of the evidence of your senses and the conviction of your understanding.”

Source: Dead Cert (1962)

"12th Foundational Falsehood of Creationism" https://www.youtube.com/watch?v=2TkY7HrJOhc Youtube (April 19, 2008)
Youtube, Foundational Falsehoods of Creationism

The Ethics of Belief (1877), The Duty of Inquiry
Context: It might be said to the agitator, "However convinced you were of the justice of your cause and the truth of your convictions, you ought not to have made a public attack upon any man's character until you had examined the evidence on both sides with the utmost patience and care."
In the first place, let us admit that, so far as it goes, this view of the case is right and necessary; right, because even when a man's belief is so fixed that he cannot think otherwise, he still has a choice in the action suggested by it, and so cannot escape the duty of investigating on the ground of the strength of his convictions; and necessary, because those who are not yet capable of controlling their feelings and thoughts must have a plain rule dealing with overt acts.

You Can Lead an Atheist to Evidence, But You Can't Make Him Think (2009)

Quoted in Tales of the Mystic East: An Anthology of Mystic and Moral Tales Taken from the Teachings of the Saints (Radha Soami Satsang Beas, 1997), p. 208

Source: Vision in White

1780s, Letter to Peter Carr (1787)
Context: You will naturally examine first, the religion of your own country. Read the Bible, then as you would read Livy or Tacitus. The facts which are within the ordinary course of nature, you will believe on the authority of the writer, as you do those of the same kind in Livy and Tacitus. The testimony of the writer weighs in their favor, in one scale, and their not being against the laws of nature, does not weigh against them. But those facts in the Bible which contradict the laws of nature, must be examined with more care, and under a variety of faces. Here you must recur to the pretensions of the writer to inspiration from God. Examine upon what evidence his pretensions are founded, and whether that evidence is so strong, as that its falsehood would be more improbable than a change in the laws of nature, in the case he relates. For example in the book of Joshua we are told the sun stood still several hours. Were we to read that fact in Livy or Tacitus we should class it with their showers of blood, speaking of statues, beasts, etc. But it is said that the writer of that book was inspired. Examine therefore candidly what evidence there is of his having been inspired. The pretension is entitled to your inquiry, because millions believe it. On the other hand you are astronomer enough to know how contrary it is to the law of nature that a body revolving on its axis as the earth does, should have stopped, should not by that sudden stoppage have prostrated animals, trees, buildings, and should after a certain time have resumed its revolution, & that without a second general prostration. Is this arrest of the earth's motion, or the evidence which affirms it, most within the law of probabilities?