Justin Martyr, First Apology 44

The holy prophetic Spirit taught us these things. Through Moses he spoke to the first created man, saying, "Behold, the good and the evil are before you; choose the good." And again through Isaiah, another prophet, it was spoken from the face of the Father of all and Master God: "Wash yourselves, become clean, remove your evil deeds from before my eyes; cease to do evil, learn to do good; seek justice, correct oppression; bring justice to the fatherless, plead the widow's cause. Come now, let us reason together, says the Lord: though your sins are like scarlet, they shall be as white as wool; though they are red like crimson, they shall become like snow. If you are willing and obedient, you shall eat the good of the land; but if you refuse and rebel, you shall be devoured by the sword; for the mouth of the Lord has spoken" (Isaiah 1:16-20).

The earlier statement, "The sword shall devour you," does not mean that those who disobey will be killed by physical swords. Rather, the sword of God is fire, and its fuel is those who choose to practice evil deeds. That is why it says, "The sword shall devour you; for the mouth of the Lord has spoken." If it were speaking of a sword that cuts and immediately destroys, it would not have said "shall devour." So Plato also, when he said, "The cause lies with the one who chooses; God is blameless," took this from Moses the prophet, for Moses is older than all the Greek writers.

Everything that philosophers and poets have said about the immortality of the soul, or punishments after death, or the contemplation of heavenly things, or similar doctrines, they received their starting points from the prophets and were able to understand and explain them. Hence there appear to be seeds of truth among all people; but they are refuted because they did not understand accurately, whenever they speak contradictions against themselves.

Therefore, when we say that future things were prophesied, we do not say it because they happen by the necessity of fate. We say it because God is foreknowing; he knows what will be done by all people, and it is a doctrine with him to reward each person according to their deeds. He foretells through the prophetic Spirit the things that will come upon each person according to their deeds, always bringing the human race to knowledge and remembrance, showing that he cares for them and provides for them.

But by the operation of evil demons, death was ordained against those who read the books of Hystaspes or the Sibyl or the prophets, so that through fear they might turn people away from acquiring knowledge of good things and keep those who serve idols in bondage. They were not able to accomplish this in the end. For we approach these writings fearlessly, and we bring them to you, as you see, for examination, knowing that they will appear pleasing to all. Even if we persuade only a few, we will have gained the greatest things; for like good farmers, we will receive the reward from the Master.