Why are angels called God's secret agents?
became popular from a book written
by Billy Graham wherein he writes
about how angels are our protectors
essentially working undercover for
God carrying out various missions.
"The angels are the dispensers and
administrators of the divine
beneficence toward us; they regard
our safety, undertake our defense,
direct our ways, and exercise a
constant solicitude that no evil
befall us" --John Calvin" (Angels
God's Secret Agents, Billy
Graham, 1986, introductory page).