On Prayer 31.6

And just as the power of Jesus, the spirit of Paul and those like him, and the angels “of the Lord” who encamp “around” each of the saints journey with and come together with those who gather genuinely, so we must conjecture that, if someone is unworthy of a holy angel and gives himself to an angel of the devil through his sins and his contempt of God in breaking the law—such a person, as long as those like him are few, will not long escape the notice of the providence of the angels, who, serving the divine will, oversee the church and bring the faults of such a one to the knowledge of the many. But if such people become numerous and come together in human factions, busying themselves with something rather worldly, they will not be watched over. This is shown in Isaiah when the Lord says, “Not even if you come to appear before me”; for “I will turn away my eyes from you,” he says, “and even if you multiply your supplication, I will not hear you.” For perhaps instead of the twofold company of holy men and blessed angels mentioned before, there comes to be in the same place a twofold assembly of impious men and evil angels; and of the gathering of such people it might be said by the holy angels and by holy men: “I have not sat with the council of vanity, and I will not go in with transgressors; I have hated the assembly of evildoers, and I will not sit with the impious.”