What Is Unbelief?

St. Hilary of Poitiers (c. AD 315-67):

"All unbelief is foolishness, for

it takes such wisdom as its own finite perception can attain,

and measuring infinity by that petty scale,

concludes that what it cannot understand must be impossible.

Unbelief is the result of incapacity engaged in argument."

—De Trinitate, III.24, cited in Douglas Kelly, Systematic Theology, vol. 1, p. 19.