Evolutionary underpinning of spirituality

Although we've discussed before, I feel like now there's stronger clarity about why humans are spiritual... because it's valuable to encode arbitrary beliefs... but very difficult if there is no spiritual component to the mind. "Religiosity" is a parameter nature sets genetically (that's been studied). I figure if it's too high the individual can loose track of reality (reducing fitness), too low and the individual has trouble carrying belief systems (closer to my end of the spectrum) (also reducing fitness).