From the Apology (39):

“We are a body knit together as such by a common religious profession, by unity of discipline, and by the bond of a common hope. We meet together as an assembly and congregation, that, offering up prayer to God as with united force, we may wrestle with Him in our supplications. This violence God delights in. We pray, too, for the emperors, for their ministers and for all in authority, for the welfare of the world, for the prevalence of peace, for the delay of the final consummation.”

Mark Burrows comments that this passage reflects “the apologist’s premise that the pax romana represents a universal peace.”

Again, from chapters 31-32:

“But we merely, you say, flatter the emperor, and feign these prayers of ours to escape persecution. Thank you for your mistake, for you give us the opportunity of proving our allegations. Do you, then, who think that we care nothing for the welfare of Cæsar, look into God’s revelations, examine our sacred books, which we do not keep in hiding, and which many accidents put into the hands of those who are not of us. Learn from them that a large benevolence is enjoined upon us, even so far as to supplicate God for our enemies, and to beseech blessings on our persecutors. Who, then, are greater enemies and persecutors of Christians, than the very parties with treason against whom we are charged? Nay, even in terms, and most clearly, the Scripture says, Pray for kings, and rulers, and powers, that all may be peace with you. For when there is disturbance in the empire, if the commotion is felt by its other members, surely we too, though we are not thought to be given to disorder, are to be found in some place or other which the calamity affects.

“There is also another and a greater necessity for our offering prayer in behalf of the emperors, nay, for the complete stability of the empire, and for Roman interests in general. For we know that a mighty shock impending over the whole earth— in fact, the very end of all things threatening dreadful woes— is only retarded by the continued existence of the Roman empire. We have no desire, then, to be overtaken by these dire events; and in praying that their coming may be delayed, we are lending our aid to Rome’s duration. More than this, though we decline to swear by the genii of the Cæsars, we swear by their safety, which is worth far more than all your genii. Are you ignorant that these genii are called Dæmones, and thence the diminutive name Dæmonia is applied to them? We respect in the emperors the ordinance of God, who has set them over the nations. We know that there is that in them which God has willed; and to what God has willed we desire all safety, and we count an oath by it a great oath. But as for demons, that is, your genii, we have been in the habit of exorcising them, not of swearing by them, and thereby conferring on them divine honour.”