Jesus tells us to love our enemies. In some parts of the world, people live in situations where this challenge to love enemies is radical because they experience people who aggressively want to hurt them, even physically. The Christian tradition has many examples of those who have loved their enemies.
For instance, in September, 2006, in Mogadishu, an Italian Consolata Sister Leonella was crossing the road from the hospital where she worked. She was shot with seven bullets by two men. As she died, she said three times, “I forgive.” We can think of the Dominican bishop of Algiers, Pierre Claverie, who promoted peaceful dialogue between Christians and Muslims and who was killed by a bomb planted in his garage in 1996.
For many of us, ‘enemies” do not be hurt us in such an aggressive way. Perhaps, they are not really “enemies” but people whom we perceive have offended us, intentionally or unintentionally, or whose ideas are opposed to ours, or with whom we continually are in disagreement or conflict.
Whatever the cause, we find it difficult to interact with them. Nevertheless, Jesus says that we should love not just those who are related to us and those who do good to us, but even those who oppose us. Disciples of Jesus are challenged how to find a positive way with which to interact with everyone.
When St. Thomas Aquinas explains what Jesus is teaching, he uses two words: affectus, meaning our interior disposition and effectus, meaning the actions that we do. What should we give to every one? Thomas answers: “compassion from the heart, or a kind word from the mouth, or wisdom from the mind” (Commentary on Gospel of Saint Matthew).
Thomas says that “everyone is bound to love by affect (interior disposition), but to love everyone by effect (action) when they have necessity” (Commentary on Gospel of Saint Matthew). Our interior disposition towards others should be love and we should be disposed to help even our “enemies” if they are in genuine need.
There is a higher standard for those who seriously seek the “perfection” that Jesus invites His disicples to, "Be perfect as your heavenly Father is perfect." Thomas states “The perfect should love their enemies perfectly outside of necessity, by affect and effect” (Commentary on Gospel of Saint Matthew).
One of the natural reasons why we should love our enemies is that we share the same nature: “And because morals are perfected in love of neighbor: "He that loves his neighbor has fulfilled the law" (Rom 13:8), Jesus urges love of anyone near to you and conformed in nature, as even enemies are” (Commentary on Gospel of Saint Matthew).
By loving our enemies, we imitate the Father, whom Jesus declares pours the sun and the rain on the just and the unjust: “that you may be children of your Father.” According to Thomas, Jesus means more than physical sun and rain: “The sun can be signified the influence of divine goodness; by rain the heavenly manifestation of truth. As if to say: If you are like your heavenly Father, you will bestow benefits on the good and on the wicked” (Commentary on Gospel of Saint Matthew). Each one of us has the possibility of being an agent of goodness and truth. We imitate the Father when we bestow our goodness and truth on everyone.
We may love a friend for a variety of reasons but “God is the only reason for loving an enemy” (2a2ae. 27, 7). Thomas affirms that: “our love for God is proved to be all the stronger through carrying a person’s affections to things that are the furthest from him, namely to the love of enemies” (2a2ae. 27, 7). Thomas uses the example of a fire in a furnace. The more powerful the fire and furnace, the further does its heat reach: “Our love for God is proved to be so much the stronger, as the more difficult are the things we accomplish for its sake” (2a2ae. 27, 7).
This doesn’t mean we should not love our friends as well: “A person loves those who are more closely united to him with more intense affection as to the good he wishes for them… We love in more ways those who are more nearly connected with us” (2a2ae. 26, 7). Nevertheless, even friendship can be brought closer to God when we love for God’s sake: “The love of our friends is meritorious, if we love them for God’s sake and not merely because they are our friends” (2a2ae. 27, 7 ad 1).
Thomas says that “to love his enemy for God’s sake, without it being necessary for him to do so, belongs to the perfection of charity. For since man loves his neighbor our of charity, for God’s sake, the more he loves God, the more does he put his enmities aside and shows love towards his neighbor: if we loved a certain man very much, we would love his children though they were unfriendly towards us. (2a2ae. 27, 7).
St. Thomas declares, “To love our enemies absolutely in the individual, and to assist them, is an act of perfection” (2a2ae. 83, 8).
Loving our enemies includes praying for them: “To pray for another is an act of charity. We are bound to pray for our enemies in the same way as we are bound to love them” (2a2ae. 83, 8). St. Thomas explains that we should not exclude our enemies from our general prayers as an obligation. Furthermore, “It is an act of perfection to pray for enemies individually (2a2ae. 83, 8).
St. Thomas affirms: “Outside of urgency to show favors or signs of love to an enemy belongs to the perfection of charity, whereby we not only beware of being overcome by evil, but also wish to overcome evil by good, which belongs to perfection; for then we not only beware of being drawn into hatred on account of the hurt done to us but purpose to induce our enemy to love us on account of our kindness” (2a2ae. 25, 9).
Denis Vincent Wiseman, O.P.
The quotations from St. Thomas Aquinas’ Commentary on the Gospel of St. Matthew were done by R.F. Larcher, O.P. The full text may be found on the web site of the Dominican House of Studies, Washington, D.C.: http://dhspriory.org/thomas/
 The references to the Summa Theologiae give the part of the Summa. This is the Secunda secundae, the second part of the Second part of the Summa. It is question 27 and the 7th article in that question.