Fear of God is of two kinds. The first is generated in us by the threat of punishment… The second kind of fear is linked with love and constantly produces reverence in the soul, so that it does not grow indifferent to God because of the intimate communion of its love.
This passage articulates the foundational Philokalic typology of two fears — punitive and filial — establishing their developmental sequence from purgation through dispassion to love.
, The Philokalia, Volume 2, 1981thesis