External factors may also hamper the natural awareness of God and contribute to a descent into atheism. In his book Faith of the Fatherless: The Psychology of Atheism, New York University psychologist Paul Vitz, a onetime atheist, examines the lives of the major atheists of the modern period, including Hobbes, Hume, Voltaire, Feuerbach, Nietzsche, Sartre, Camus, Russell, and Freud. He found they had something in common: a broken relationship with their father. Whether by death, departure, abuse, or some other factor, the father relationships of all these well-known atheists were defective. Vitz also examined the lives of prominent theists during the same period (Pascal, Reid, Burke, Berkeley, Paley, Wilberforce, Kierkegaard, Schleiermacher, Newman, Chesterton, and Bonhoeffer, among others). In every case, he found a good relationship with the father or at least a strong father figure.
-from "Unreasonable Doubt" by Jim Spiegel in the January 2011 issue of Christianity Today.