Was Lavoisier a sceptical Enlightenment rationalist or (as a number of websites insist) a Christian believer?
This is a difficult question to answer: in the his writings and in his many letters which have come down to us, there is almost no mention of religion.
However, in October 1791 he penned the following tirade against clerical education:
Public education as it exists in almost the whole of Europe, has been set up not to form citizens but to produce priests, monks and theologians. The spirit of the Church has always opposed innovation, and because the first Christians spoke and prayed in Latin...it has been deemed necessary to pray in Latin to the end of time. For this reason the European education system is almost entirely directed towards teaching Latin.
If one reviews the public acts, the thesis of metaphysics and ethics defended in the Colleges, one sees that they are only an introduction to theology, that theology is the highest form of knowledge, which shapes whole education system.
The only goal of public education is to form priests. For a long time the Colleges were open only to those who studied for the priesthood. Since an ecclesiastical career led to honour and fortune, the catholic nations were naturally divided into two classes: ecclesiastics, who had all the instruction and the illiterate who formed almost all the rest of the nation. This is how, at first by chance, and then by strategy, all the means to destroy errors and prejudices was concentrated in the hands of those who had an interest in propagating them.
"On one of my visits,going through a pile of unsorted papers...I laid hands on a notebook composed of several sheets of rough paper, on which Lavoisier, in a rapid hand, with numerous crossings out, had scribbled down some notes entitled "Réflexions sur le plan d'instruction publique présenté... par M. Talleyrand-Périgord".
"Ho ho! I cried to myself, "this could be interesting"
And so it proved. Grimaux acknowledged that "the manuscript reveals a Lavoisier that I did not know, an anti-clérical as they say today". Guillaume borrowed the document and took the precaution of having it photographed - in those days a huge palaver which involved the services of a technical laboratory at the École Normale: ""Now, whatever zealous defenders of the Church might do in the future, this irrefutable evidence of Lavoisier's philosophical opinions would be safe from annihilation". In fact in 1894 Grimaux threw caution to the wind and allowed Guillaume to publish the opening paragraphs in the introduction to his Procès verbaux du Comité d'instruction publique. Finally in March 1907, following a provocative right-wing speech at the pantheonisation of the chemist Marcellin Berthelot, Guillaume decided to defend Lavoisier's Revolutionary credentials by publishing the whole text. (The speaker, Henry Roujon, had remarked that "nowadays we put people in the Pantheon without guillotining them first'").
Lavoisier's religious opinions?
As a liberal Revolutionary, Lavoisier clearly supported the destruction of clerical privilege and the nationalisation of Church property. He also advocated a practical, secular education system . However, there is no suggestion his anti-clericalism went as far as dechristianisation; his love of order and strict adherence to constitutional legality committed him to the Civil Constitution of the Clergy.
In pre-Revolutionary years, he adhered to social proprieties: Grimaux notes that, as lay patron of the chapel at Freschines, he had nominated, by an act of 7th August 1781, a chaplain, the abbé Bellavoine, to whom he gave annually 290 livres. ( Grimaux, p. 53. nt 2) According to Madame Lavoisier, he also regularly attended the church in Villefrancoeur.
Lavoisier's personal beliefs elude us. Grimaux was able to muster only one - much cited - piece of evidence in favour of his orthodox Christianity: in a letter of 20th August 1788, Lavoisier acknowledges the gift of a work of apologetics by the English theologian Edward King : "You wage a noble cause in defending the revelation and the authenticity of the Scriptures; and what is remarkable is that you now use for defence the very weapons that have many times been employed in attack" (see Grimaux, p.53). Before reading too much into a throwaway sentence, it is worth noting that Edward King (1735-1807) was a prominent figure in scientific circles: a member of the Royal Society, a mineralogist and an early supporter of Lavoisier's system of chemical nomenclature - certainly a correspondent to be treated politely. Lavoisier - who didn't read English - is probably just parroting back the title of King's 1788 book: Morsels of criticism, tending to illustrate some few passages in the Holy Scriptures upon philosophical principles and an enlarged view of things.
Up to this point my story contains nothing extraordinary; but what follows is rather astonishing. One day these two Farmers-General came to find their colleagues, and the academician declared to them in a loud voice, "We have come to let you know that, on reflection, you have taken the correct course, the only appropriate action in the circumstances".
At first the Farmer-Generals were astonished by this pronouncement which they took for a joke in bad taste; they replied, that the situation was too grave for joking and their remaining time too precious to waste in disputation. The grave yawns open before us, they added;you should not disturb our contemplation of the great and moving truths it brings to mind. Even though you do not share it, you ought to respect our conviction that a new eternal life awaits us on the other side of the grave.
No, no, the academic replied with emotion; we are not joking. We approve your state of mind in all seriousness.
The Farmers-General were then convinced that their two colleagues had indeed had a great change of opinion; they rejoiced and embraced them. One of them then addressed the academician:
What you say is true; we are doing the right thing; but we will not hide from you our concern about the worth of our conversion, after we have led disordered and sinful lives in the world. Might our conversion not be considered forced, since we face certain imminent death? Would we feel the same if we were still free, in the noise and bustle of society, where people think of everything except death?
The academician, who was naturally eloquent, replied with a noble and consoling speech on God's infinite mercy and goodness, and the merits of the Christian redeemer. His listeners were reduced to tears found themselves filled with a sweet hope.
Almanach des gens de bien, contenant des anecdotes peu connues, pour servir a l'histoire des evenemens de ces derniers tems (1795) [On Google Books]
Monjoie gives as his source a letter of Étienne-Marie Delahante to a member of his family. This is plausible - Delahante's two brothers-in-law, Charles and Alexandre de Parseval de Frileuse, were extremely pious and, according to the family memoirs, Delahante himself turned more to religion as a result of his experiences..
Scheler and Smeaton conclude judiciously that it is not really possible to know whether Lavoisier experienced genuine change of heart or simply acted out of regard for his fellow-prisoners: "his bitterness and his compassion were surely sufficient to reunite him with his companions in misfortune during the closing scenes of the tragedy” (Scheler and Smeaton 1958, p. 153)
Certainly there are no expressions of Christian belief in Lavoisier's last letters, penned in extremis. His hopes are all for the recognition of posterity. The most we have is a passing allusion to a possible afterlife in a letter to his wife. Writing in early December, he enjoins her not to be mourn him: he has accomplished all his ambitions, and adds, without a great deal of conviction, "we can still hope to be together again..."
The letter from Talleyrand, and the surviving text of Lavoisier's MS are available in full in "Lavoisier", Nouveau dictionnaire de pédagogie et d'Instruction primaire (1911) e-version on the IFE website.
For the context, see Jean Pierre Poirier, Lavoisier: chemist, biologist, economist (Engl. trans. 1998) Available on Internet Archive: p.336-345