Faith is knowing something must be true given what we already know. For instance, we know that when we bring a magnet close to a compass, the needle moves. Therefore, we know that there's an invisible force moving it.
Another example, although a more sophisticated one, is knowing that matter displays intelligence consistently and coherently across multiple domains, such as subatomic matter and organic matter. We can see that intelligence must be ubiquitous because it displays itself everywhere. As far as we can tell, it’s universal.
Before the Scientific Revolution, religion and science were indistinguishable. Their separation was a negotiated divorce driven as much by politics as it was by the desire for intellectual autonomy. Many credit the rigorous scholarship of theology for establishing the methodological discipline that would make scientific research possible.
Viewed this way, the word "faith" could be a proto-scientific term for deductive reasoning—"this, therefore that"—following a causal chain to its set of possible outcomes. In the case of universal intelligence, the evidence is overwhelming, so we can infer that it is structurally coherent across all domains. We don't know this for sure, but it's a compelling argument. The fact that we have yet to discover a unified theory of everything shows that even though we lack definitive proof, we have a high degree of confidence that it exists.
We take it on faith.
An early example of the concept of universal intelligence is Deuteronomy’s “Hear, O Israel, the Lord our God is ONE Lord.” The word “Lord” implies rulership or laws. The overall implication is that reality is a unified system governed by a coherent set of principles. The passage in Deuteronomy goes on to command God’s people to keep this concept foremost in their minds as the most important principle in establishing God’s kingdom on Earth. This can be interpreted as the perfection of civilization (the kingdom) through the recognition that all aspects of life, both social and technological, are interdependent. Changes effected in one domain affect all others, as in Chief Seattle’s “Web of Life.”