In the latter half of philosophical fragments, Johannes Climacus discusses the differences between the necessary and the contingent. He argues that there exists only one truly necessary being, and that being is the god. According to Climacus, that which is historical is contingent and might not have been. Following this line of argument, Climacus progresses into another description of the paradox of faith:
Christianity is the only historical phenomenon that despite the historical—indeed, precisely by means of the historical—has wanted to be the single individual's point of departure for his eternal consciousness, .... (p. 109)
According to Climacus, there is and has only ever been one necessary being, and that is the god. This god, by nature of his necessity, never came into existence, but is in its very nature, being. In more common terminology, only the god is eternal. Anything that comes into existence was merely possible before it existed, and actual after it came into being. This also includes anything which does not yet exist. If it will come into existence, it is now possible, but does not exist. How can it, therefore, be eternal? It cannot. Thus, in the same way, because something came into existence at a specific historical and temporal moment, it could not have been, and cannot be necessary; it could not have been and cannot be eternal. "Coming into existence is a change, but since the necessary is always related to itself and is related to itself in the same way, it cannot be changed at all" (p. 74).
Climacus continues, and begins to deal with the past. Some would argue that, since the past is unchangeable, it is therefore necessary. For Climacus, this argument is invalid. "The unchangeableness of the past is that its actual 'thus and so' cannot become different, but from this does it follow that its possible 'how' could not have been different" (p. 77)? In essence, Climacus states that the past might have been different, and that it might not have been at all. It is the unchangeable and eternal nature of the god that attests to its necessity.
Climacus' reasoning eventually develops into a puzzling paradox: how can the god, who is necessary, also have become part of the contingent and historical? In his answer, Climacus proposes one of the foundations and inherent characteristics of faith. By his own admission, the god is necessary and eternal, and therefore not historical and temporal. The god is then born human and enters into the historical, into the contingent, in order to show Man his error and provide the condition under which Man can learn the truth. The resolution is attained in faith. Faith in the paradox that the god can be necessary and historical at the same time is, in its essence, a faith in the absurd.
As a result of its basis in paradox, Climacus' description is truly faith and not merely belief. One who truly has faith cannot merely "love the omnipotent one who does miracles" (p. 108), but must also "love the one who abased himself in equality with you" (p. 108). Only in this way can true faith be had; only in this way could Christianity want "to base his [the individual's] happiness on his relation to something historical" (p. 109).