The consequences of this unprecedented evolutionary transition for human religious and spiritual development must be understood on many levels as well. There are reasons to believe that the way language refers to things—symbolic reference— provides the crucial catalyst that initiated the transition from species with no inkling of meaning in life to a species where questions of ultimate meaning have become core organizers of culture and consciousness. Symbolic reference is reference to things and ideas that is mediated by an intervening system of symbol-symbol relationships, as well as conventions of use that allow there to be considerable conceptual “distance” between a sign vehicle and its object of reference. Unlike icons, which refer by means of structural similarities between a sign vehicle and its object, or indices, which refer via their physical contiguity or invariant causal correlation with their object, this conceptual “distance” is an intermediate referential step that allows the form of symbols to be entirely independent of the objects to which they refer.

From J. Wentzel Vrede van Huyssteen, Encyclopedia Of Science And Religion

Symbolic reference is thus both arbitrary and capable of providing considerable displacement and abstraction. Displacement refers to the capacity to refer to things distant in space or time, and abstraction refers to the ability to represent only the more spare and skeletal features of things, including their logical features, such as whether they are even ontologically existent. So it is with the evolution of this symbolic capacity that it first becomes possible to represent the possible future, the impossible past, the act that should or shouldn’t take place, the experience that is unimaginable even though representable. These capacities are ubiquitous for humans and largely taken for granted when it comes to spiritual and ethical realms, but this is precisely where crucial differences in ability mark the boundary that distinguishes humans from other species.