Given my recent series on existential theology, it's interesting to note that at the start of Introduction to Christianity Ratzinger connects faith to meaning-making. That was a very common move theologians made back in the 60s, which is less common today, and Ratzinger had his own spin on it.
(A note in what follows. Typical of the time, Ratzinger uses the word "man" to mean "humanity." That usage is a bit dated, but I've left his quotes unedited.)
To start, Ratzinger describes how faith in something, from a meaning-making perspective, is necessary for decision-making. Some value has to guide our choices. The mind needs some "traction," a vision of the good, in order to move forward into life. Ratzinger:
[E]very man must adopt some kind of attitude toward the realm of basic decisions, decisions that, by their very nature, can only be made by entertaining belief. There is a realm that allows no other response but that of entertaining belief, and no man can completely avoid the realm. Every man is bound to have some kind of "belief."
What, then, is the nature of this "belief"? For Ratzinger, "belief" involves taking a "stand" concerning the basic meaning of reality:
[Belief] is a human way of taking up a stand in the totality of reality, a way that cannot be reduced to knowledge and is incommensurable with knowledge; it is the bestowal of meaning without which the totality of man would remain homeless, on which man's calculations and actions are based, and without which in the last resort he could not calculate and act, because he can only do this in the context of a meaning that bears him up. For in fact man does not live on the bread of practicability alone; he lives as man, and precisely in the intrinsically human part of his being, on the word, on love, on meaning. Meaning is the bread on which man, in the intrinsically human part of his being, subsists. Without the word, without meaning, without love he falls into the situation of no longer being able to live.
Further, if meaning is the bread of life, we cannot provide a meaning for ourselves, something that is self-constructed. Self-conjured meaning is fragile, self-referential, and arbitrary. Ratzinger observes:
Essentially, [belief] is entrusting oneself to that which has not been made by oneself and never could be made and which precisely in this way supports and makes possible all our meaning...
No one can pull himself up out of the bog of uncertainty, of not being able to live, by his own exertions; nor can we pull ourselves up, as Descartes still thought we could, by a cogito ergo sum, by a series of intellectual deductions. Meaning that is self-made is in the last analysis no meaning. Meaning, that is, the ground on which our existence as a totality can stand and live, cannot be made but only received.
So, meaning-making is necessary for human life, but we cannot create our own meaning without falling into self-referentiality. We need to receive meaning from outside ourselves, a meaning upon which we can stand. All this brings us to Ratzinger's oft-quoted description of belief:
For to believe as a Christian means in fact entrusting oneself to the meaning that upholds me and the world; taking it as the firm ground on which I can stand fearlessly...It means affirming that the meaning we do no make but can only receive is already granted to us, so that we have only to take it and entrust ourselves to it.
