“Difference of opinion is advantageous in religion. The several sects perform the office of a Censor morum over each other. Is uniformity attainable? Millions of innocent men, women, and children, since the introduction of Christianity, have been burnt, tortured, fined, imprisoned; yet we have not advanced one inch towards uniformity. What has been the effect of coercion? To make one half the world fools, and the other half hypocrites. To support roguery and error all over the earth. Let us reflect that it is inhabited by a thousand millions of people. That these profess probably a thousand different systems of religion. That ours is but one of that thousand. That if there be but one right, and ours that one, we should wish to see the 999 wandering sects gathered into the fold of truth. But against such a majority we cannot effect this by force. Reason and persuasion are the only practicable instruments. To make way for these, free enquiry must be indulged; and how can we wish others to indulge it while we refuse it ourselves.”

“When we see religion split into so many thousand of sects, and I may say Christianity itself divided into its thousands also, who are disputing, anathematizing and where the laws permit burning and torturing one another for abstractions which no one of them understand, and which are indeed beyond the comprehension of the human mind, into which of the chambers of this Bedlam would a man wish to thrust himself.[Letter to George Logan, 12 November 1816]”

“I am for freedom of religion, and against all maneuvers to bring about a legal ascendency of one sect over another.”

“I agree with yours of the 22d that a professorship of Theology should have no place in our institution. but we cannot always do what is absolutely best. those with whom we act, entertaining different views, have the power and the right of carrying them into practice. truth advances, & error recedes step by step only; and to do to our fellow-men the most good in our power, we must lead where we can, follow where we cannot, and still go with them, watching always the favorable moment for helping them to another step.[Comment on establishing Jefferson's University of Virginia, a secular college, in a letter to Thomas Cooper 7 October 1814]”

“I wish that all nations may recover and retain their independence; that those which are overgrown may not advance beyond safe measures of power, that a salutary balance may be ever maintained among nations, and that our peace, commerce, and friendship, may be sought and cultivated by all. It is our business to manufacture for ourselves whatever we can, to keep our markets open for what we can spare or want; and the less we have to do with the amities or enmities of Europe, the better. Not in our day, but at no distant one, we may shake a rod over the heads of all, which may make the stoutest of them tremble. But I hope our wisdom will grow with our power, and teach us, that the less we use our power, the greater it will be.”

“I write nothing for publication, and last of all things should it be on the subject of religion. On the dogmas of religion as distinguished from moral principles, all mankind, from the beginning of the world to this day, have been quarrelling, fighting, burning and torturing one another, for abstractions unintelligible to themselves and to all others, and absolutely beyond the comprehension of the human mind. Were I to enter on that arena, I should only add an unit to the number of Bedlamites.[Letter to Mathew Carey, 11 November 1816]”

“More we know more we know our ignorance. Darkness can be perceived with the help of light.Facts are stranger than fiction.Have you ever thought why there are many religions and there is only one science on the Earth? Devotees of different religions follow different customs, rituals, prayers, attributes of gods, etc. Each religion has many sects; these sects are further divided as per the geographical locations of the devotees. Thus, religious concepts of different people are altogether different. For example, people of one religion sacrifice animals to appease their gods; whereas, people of other religion appease their gods through the service of those animals. To take another example, the idol worship is core of one religion; whereas, the other religion has imposed a taboo over idol worship. One can say that this discrepancy among religions is due to the fact that religions originated in different geographical locations. Not only religions, science was also conceived by the scientists of diverse origin. However, all those unconnected scientists discovered exactly similar scientific principles. Have you ever heard Indian science, British science, or American science? All over the world, many pioneer scientists discovered their principles and later other scientists attested those. If some principle was found incorrect, soon its inventor accepted the truth. There is one concrete reason behind existence of many religious concepts and only one science on the Earth. About one thing or concept, there is only one truth but there can be many lies.”