Tormented by growing economics hardship and insecurity, the urban poor of the third and fourth century empire turned more and more from the boisterous and unlikely gods of the Greco-Roman Olympic cult - Jupiter, Juno, Apollo, Minerva and the rest - to compelling new religions that offered release from individual guilt and the promise of personal salvation and eternal life. These new 'mystery religions' originated in the older, Eastern cultures that Rome had absorbed into its empire. From Egypt came the cult of the goddess Isis, from Persia Christianity.
The gods and goddesses of Olympus survived for a time but in altered form. During the third century, all that was vital in the traditional pagan cults was incorporated into a new philosophical scheme called "Neoplatonism" (based loosely on the much earlier though of the Greek philosopher Plato). Neoplatonism was the creation of the third century philosopher Plotinus, one of the most influential minds of the Romans imperial era. Plotinus taught the doctrine of one god, who was infinite, unknowable and unapproachable, except through a mystical experience. This deity was the ultimate source of everything, spiritual and physical. All existence was conceived of as a series of circles radiating outward from him, like concentric ripples in a pond, diminishing in excellent and significance as they grew more distant from their divine source. Human reason, which the Greeks had earlier exalted, now lost its fascination, for at the core of reality was a god that lay beyond reason's scope.
Plotinus and his followers regarded the multitudes of pagan gods and goddesses as crude but useful symbols, pointing to the overarching Neoplatonic god. Though poorly suited to the deepening mood of otherworldliness, the pagan cults acquired new life under under the canopy of Neoplatonic philosophy, which brought them into line with the trend toward mysticism and monotheism. The distinction between Jupiter and the new Eastern deities was steadily blurring.