And if I glance around at their examples-(examples) of some David heaping up marriages for himself even through sanguinary means, of some Solomon rich in wives as well as in other riches-you are bidden to "follow the better things; " and you have withal Joseph but once wedded, and on this score I venture to say better than his father; you have Moses, the intimate eye-witness of God; you have Aaron the chief priest.
Light has nothing in common with darkness, and there is no agreement between Christ and Belial. The person who does good has Christ, the true light, and not darkness or Belial. But the person who does evil is from Belial and darkness and has not seen God or had any knowledge of him.
Beloved, do not imitate what is evil, but what is good. Whoever does good is from God; whoever does evil has not seen God.
"do not imitate what is evil." Since there is no unity of light with darkness, nor any unity between Christ and Belial (2 Cor. 6:14), it is not appropriate for one who has been illuminated by the knowledge of Christ to mix with darkness through the imitation of the wicked, or through their lustful and shameless works. For just as he who does good is from God, and has composed the eye of his understanding in the light of that knowledge, and thus is wholly light, and sees God, who is true light, and is seen by others as a luminary in the world (Phil. 2:15), sustaining the Word of life; so also he who does evil, walking in darkness, cannot see God, that is, cannot do the things that are of God, nor can he be seen by others, if he rebukes or corrects anyone: but all hate and abominate him, according to that wise oracle: "I have hated iniquity and have abominated it." (Ps. 118:163 LXX)
[AD 220] Tertullian on 3 John 1:11