Charles Oman writes about the spiritual aspect of the War on the Peninsula, particularly as it affected Wellington’s British Army:
I think that even if the Wesleys had never lived, there would yet have been a strong reaction in favour of godly living and the open profession of Christianity, in consequence of the blasphemous antics of the French Revolution. Nothing in that movement so disgusted Englishmen (even those of them who were not much given to practical religion) as the story of the “Goddess of Reason,” enthroned on the high-altar of Notre Dame, at the time when an orgy of bloodshed was making odious the flatulent talk about humanitarianism and liberty which was the staple of Revolutionary oratory. The peculiar combination of insult to Christianity, open evil living, and wholesale judicial murder, which distinguished the time of the Terror, had an effect on observers comparable to nothing else that has been seen in modern times.
Even men who had not hitherto taken their religion very seriously, began to think that a hell was logically necessary in the scheme of creation for beings like Chaumette or Hebert, Fouquier Tinville or Carrier of the Noyades. And, we may add, a personal devil was surely required, to account for the promptings of insane wickedness which led to the actions of such people. A tightening up of religious observances, such as the use of family prayer and regular attendance at Church, was a marked feature of the time. It required some time for the movement to spread, but its effect was soon observable. It naturally took shape in adhesion to Evangelical societies within the Church of England, or Methodist societies without it; since these were the already existing nuclei round which those whose souls had been stirred by the horrors in France and the imminent peril of Great Britain would group themselves.
Very soon the day was over in which “enthusiasm” was the dread of all normal easy-going men. Something more than the eighteenth century religious sentimentalism, and vague spiritual philosophy, was needed for a nation which had to fight for life and empire against the French Republic and all its works. Those methods of thought were sufficiently discredited by the fact that there was a touch of Rousseau in them : it was easy to look over the Channel, and see to what a belief in some nebulous Supreme Being, and in the perfectibility and essential righteousness of mankind at large, might lead. The God of the Old Testament was a much more satisfactory object of worship to the men who had to face the Jacobin, and Calvinism has always proved a good fighting creed. If ever there was a justification for a belief that the enemy were in a condition of complete reprobation, and that to smite them was the duty of every Christian man, it was surely at this time. The conviction of the universahty of sin and the natural wickedness of the human heart was the exact opposite and antidote to the optimistic philosophy of the eighteenth century, and to its belief that man is essentially a benevolent being, and that if he sometimes breaks out into deplorable violence “tout comprendre est tout pardonner.”
We’ve reached the point that the men of the West are beginning to grasp the limits of reason again. But they have not yet really begun to realize the ease with which it is naturally turned to evil in the absence of Jesus Christ.