According to Tocqueville's discourse on “Democracy in America”, Christian bring the values of freedom and equality to America. What causes the religious values and political philosophy cooperate to advance at the same time, and make America become the best democratic country, is the policy of separating religion from politics. Furthermore, in the affections of religion and the “principle of self-interest rightly understood”, American combine the material enjoyment and the loving of freedom with the concern about public affairs, and then, they organize to participate in public affairs. Investigating contemporary society from Tocqueville's thought, what make the society out of frame are not the belief of pluralism and individualism, but lacking a social contract and value, like religion, than can link up the individual interests with the whole.