Justin Martyr, First Apology 44

The holy prophetic Spirit taught us these things. Through Moses he spoke to the first man formed, telling him that God said, "Look, the good and the evil are set before you; choose the good." Again, through Isaiah, another prophet, he spoke from the face of the Father of all and the Master God: "Wash yourselves, become clean, remove the evil deeds from your souls. Learn to do good; seek justice for the orphan, defend the widow. Come now, let us reason together, says the Lord. Though your sins are like scarlet, I will make them white as snow; though they are red as crimson, I will make them white as wool. If you are willing and obey me, you will eat the good of the land; but if you refuse and rebel, the sword will devour you, for the mouth of the Lord has spoken" (Isaiah 1:16-20).

The earlier statement "the sword will devour you" does not mean that the disobedient will be killed by literal swords. The sword of God is fire, and its fuel is those who choose to do evil. That is why it says, "The sword will devour you; for the mouth of the Lord has spoken." If it referred to a blade that cuts and destroys at once, it would not have said "will devour." So Plato also, when he said, "The cause lies with the one who chooses; God is blameless," took this from the prophet Moses, for Moses is older than every Greek writer.

All that philosophers and poets have said about the immortality of the soul, the punishments after death, the contemplation of heavenly things, or similar doctrines they drew as starting points from the prophets and were able to grasp and explain. Hence seeds of truth appear among all people; yet they are refuted because they did not understand accurately, as shown when they contradict themselves. Therefore, when we say that future events were prophesied, we do not claim they occur by the necessity of fate. Rather, God foreknows what every human will do, and with him stands a decree to repay each person according to their deeds. Through the prophetic Spirit he declares in advance what will befall each according to their actions, continually leading the human race to knowledge and remembrance, proving that he cares for them and provides for their needs.

But by the working of evil demons, death was decreed against anyone who reads the books of Hystaspes, or the Sibyl, or the prophets, so that through fear they might turn people away from gaining knowledge of the good and keep those who serve them in bondage—a plan they could not carry out to the end. For we approach those writings without fear, and we bring them to you, as you see, for examination, confident they will prove acceptable to all. Even if we persuade only a few, we will have won the greatest gain; for as good farmers we will receive our reward from the Master.