Answer:
Modern science began in the cradle of medieval Christianity. The dogma of one Creator God who has made all things through the Logos, the Word, in a rational and systematic way, underpins physics and chemistry.
Roger Bacon, St Albert the Great, Nicholas Oresme, Nicholas of Cusa, Robert Grosseteste and others laid the foundations of scientific method, experiment, and concepts like momentum.
Then we had Copernicus, Galileo, Kepler and Newton. For all of these their religious faith was fundamental, whether Catholic or Protestant.
Various Catholic writers refer to the “Endarkenment” rather than the “Enlightenment.” The philosophes - Rousseau, Diderot, d’Alembert, Voltaire etc exalted human reason and poured the acid of scepticism over religious belief and the monarchical status quo.
In championing human reason, one might point out that they ignored original sin, and humanity’s tendency to evil. When the Enlightenment theories were put into practice, coupled with scientific progress, they often proved disastrous.
The French Revolution began with the uplifting cry of Liberté, Egalité, Fraternité! Within a couple of years it had degenerated into a bloodbath, with Robespierre and the Terror 1793–94 and 25,000 dead. There was chaos and violence all over France as law and order broke down. Tumbrils rolled daily to the guillotine and the baskets filled with heads.
Then there was the ruthless suppression of the Catholic Uprising against the Revolution in the Vendée with 500,000 dead.
The Revolution ended with Napoleon’s rise to power. He then plunged the whole of Europe into a series of wars, costing millions of deaths, up to his retreat from Moscow, and finally Waterloo.
The throwing off of the shackles of Christianity coupled with technological developments and rapid industrialization led to dreadful exploitation of the poor in the factories and cities. Liberal capitalists grew extremely rich off the sweat and suffering of the poor, as Friedrich Engels described and analysed among the Irish in Manchester in 1844–46.
This oppression led to the Marxist reaction, an atheistic class war establishing the dictatorship of the proletariat and the extermination of the bourgeoisie.
In many cases the loss of the sense of God led to the abandonment of moral codes, the disintegration of family life and the slow breakdown of society.
The Enlightenment’s emphasis on human rights and the use of reason is satisfactory, but it always lacked a clear anthropology, a clear vision of the purpose of human life. Human rights are important, but so are human duties. To claim human rights while neglecting human duties is like building a wall with one hand and tearing it down with the other, as Pope John XXIII remarked.
The Enlightenment’s emphasis on liberty has often promoted mere license. This allows the rich and powerful to take advantage of the poor and vulnerable in new ways, sexually and economically.
The scientific revolution has given us much more technical power and control over nature. That power, however, needs to be used in ways which are moral, and which respect the human person. Science can never be exempt from the moral law.
Otherwise technical progress is merely the development from the caveman’s club to the nuclear bomb.