The devil tries to disrupt our hope in Christ and our love for Him in a thousand ways. Inwardly he brings afflictions on the soul by means of the evil spirits, or he fills it with foul and immoral thoughts by stirring up its memory of former sins, so as to make it grow sluggish and to despair of ever attaining salvation.
His aim is to cheat the soul into thinking that it generates these thoughts of its own accord and that they are not sown in it maliciously by an alien spirit. Or else he inflicts bodily suffering and brings on us vilification and tribulation through the agency of other people. But the more he shoots his fiery arrows at us, the more we must enkindle our hope in God, knowing with certainty that He deliberately permits souls that long for Him to suffer these things, so as to discover if they truly love Him.
~St Makarios of Egypt