Kierkegaard regarded the religious-ethical catagory of the individual as his greatest philosophic discovery. Kierkegaard's emphasis on the individual countered the "mass" moral of his contemporary philosophy which did not see the private conscience as a fundamental principle of ethics. The subjective individual in philosophy was opposed to the objective truth. But for Kierkegaard the crucial thing in faith (which it tied to truth) is the individual relation to the absolute, to God.
In Fear and Trembling Kierkegaard opposed the individual with the universal. While the universal is ethical, the individual can be either aesthetic (living for himself) or religious (living for God).