The infinite qualitative distinction (Danish: den uendelige kvalitative forskel; German: unendliche qualitative Unterschied), sometimes translated as infinite qualitative difference,^[2] is a concept coined by the Danish philosopher Søren Kierkegaard. The distinction emphasizes the very different attributes of finite and temporal men and the infinite and eternal qualities of a supreme being. This concept fits into the apophatic theology tradition and therefore is fundamentally at odds with theological theories which posit a supreme being able to be fully understood by man. The theologian Karl Barth made the concept of infinite qualitative distinction a cornerstone of his theology.^[3]

For Kierkegaard, direct communication with God is impossible, as God and man are infinitely different. He argues that indirect communication with God is the only way of communication. For example, in Christian belief, the Incarnation posits that Jesus Christ is God incarnate. The infinite qualitative distinction is opposed to rational theology in the sense that, whereas the latter argues one can prove empirically Jesus is God incarnate, the former argues that empirical evidence is ultimately insufficient in making that conclusion. The paradoxical nature of the Incarnation, that God is embodied in a man, is offensive to reason, and can only be comprehended indirectly, through faith.^[4]

Barth's book The Epistle to the Romans also emphasizes such a gulf. In the preface to the Second Edition of his commentary, Barth writes, "if I have a system, it is limited to a recognition of what Kierkegaard called the 'infinite qualitative distinction' between time and eternity, and to my regarding this as possessing negative as well as positive significance: 'God is in heaven, and thou art on earth'. The relation between such a God and such a man, and the relation between such a man and such a God, is for me the theme of the Bible and the essence of philosophy."^[5]

Kierkegaard doesn't believe God is so objective toward human beings but rather that he is the absolute subjective being. He put it this way in 1846:

The subjective thinker is a dialectician dealing with the existential, and he has the passion of thought requisite for holding fast to the qualitative disjunction. But on the other hand, if the qualitative is applied in empty isolation, if it is applied to the individual in an altogether abstract fashion, one may risk saying something infinitely decisive and be quite correct in what one says, and yet, ludicrously enough, say nothing at all. Hence it is a psychologically noteworthy phenomenon, that the absolute disjunction may be used quite disingenuously, precisely for the purpose of evasion. When the death-penalty is affixed to every crime, it ends in no crime being punished at all. So also in the case of the injunction. Applied abstractly it becomes an unpronounceable mute letter, or if pronounced, it says nothing. The subjective thinker has the absolute disjunction ready to hand; therefore, as an essential existential moment he holds it fast with a thinker’s passion, but he holds it as a last decisive resort, to prevent everything from being reduced to merely quantitative differences. He holds it in reserve, but does not apply it so as by recurring to it abstractly to inhibit existence. Hence the subjective thinker adds to his equipment aesthetic and ethical passion, which gives him the necessary concreteness. All existential problems are passionate problems, for when existence is interpenetrated with reflection it generates passion.

• Søren Kierkegaard, Concluding Unscientific Postscript, 1846 p. 313 Swenson/Lowrie translation 1941