Individualism is the idea that individuals can do more to help themselves than any government or group; that idea stands in opposition to collectivism. Individualism was popularised in the nineteenth century by the British philosopher John Stuart Mill and by his follower Auberon Herbert.
'Rugged individualism' is a term derived from 'individualism' and denotes the ideal of a righteous life in which the individual never finds that he needs help from anyone in order to remain both healthy and sane in a fallen world. In refusing the offer of the king of Sodom to take what many Bible commentators say was a rightful portion of the spoils of the war through which he rescued Lot, Abr(ah)am (Abraham) was motivated by a sense of rugged individualism in mind of God's promises to him.
Nonetheless, rugged individualism, while implicitly sought by all, is an ideal which is unattainable by mere fallen individuals (and thus by all nations made up of fallen individuals). Even Karl Marx, who was the founder of Communistic dictatorship, was driven by the hope of creating a society in which individuals lived righteously without bureaucratic oversight. In contrast to Marxian methods toward that end are those of Ayn Rand, who advocated a 'purest' branch of individualism in which the individual's secular liberty, including his functional material captital, is put in adverse relationship to the intelligent and humane extension of the dynamics of the natural family into the wider society.
The only person ever to have lived a life of rugged individualism is Jesus Christ, and he never preached individualism as such, but something of far more dense value: the spirit of the Mosaic Law, which has been God's standard to all nations since the second-youngest son of Jacob was prime minister (viceroy) in Egypt.