What was it that drew Constantine the Great, so momentously for Western civilization, toward monotheism and ultimately to Christianity? In his biography of the emperor, Ramsay MacDonald eliminates possibilities. It wasn't, for example, a personal relationship with Christ. Constantine hardly knew him:
Writing about the Donatists in 314, Constantine mentions Christ, but several considerations, and several modern scholars, suggest that the letter was drafted or edited by churchmen in the court . . .; otherwise he makes no reference to Christ until 321. That peculiarity deserves emphasis. It does much to explain the route that his spirit traveled in conversion, passing not instantaneously from paganism to Christianity but more subtly and insensibly from the blurred edges of one, not truly itself, to the edges of the other.
Nor was it the moral vision of the religion:
A decade after his conversion [Constantine] was still personally decreeing crucifixion as a punishment. The right of parents to expose unwanted children he never attacked, despite opposite views which he might have read in the Divine Institutes; and there, too, Lactantius had harshly condemned gladiatorial spectacles as "public murders," which, notwithstanding, the emperor left untouched until 325. . . . [T]he contrast is clear between his attention to the outward parts and appearances of the Church, and on the other hand his inattention to its spiritual meaning.