John Adams
August 14, 1796

Adams lays out the mechanics of why religion is particularly effective at promoting morality.

The Weather hot and dry.

One great Advantage of the Christian Religion is that it brings the great Principle of the Law of Nature and Nations, Love your Neighbour as yourself, and do to others as you would that others should do to you, to the Knowledge, Belief and Veneration of the whole People. Children, Servants, Women and Men are all Professors in the science of public as well as private Morality. No other Institution for Education, no kind of political Discipline, could diffuse this kind of necessary Information, so universally among all Ranks and Descriptions of Citizens. The Duties and Rights of The Man and the Citizen are thus taught, from early Infancy to every Creature. The Sanctions of a future Life are thus added to the Observance of civil and political as well as domestic and private Duties. Prudence, Justice, Temperance and Fortitude, are thus taught to be the means and Conditions of future as well as present Happiness.

Source(s):
Adams Family Papers: An Electronic Archive, John Adams diary 46, various loose folded sheets, 6 August 1787 – 10 September 1796 (with gaps), 2 July – 21 August 1804, The Massachusetts Historical Society.