"Blessed are the merciful, for they shall be shown mercy.
Blessed are the pure in heart, for they shall see God.
Blessed are the peacemakers, for they shall be called sons of God." -- Jesus
"Go and learn what this means, 'I desire mercy, not sacrifice.'" -- Jesus
"Pray like this: ... 'Forgive us our sins, as we forgive those who sin against us.' ... For unless you forgive those who sin against you, your Father in heaven will not forgive you." -- Jesus
The first command of the Law [in importance] is this: 'Love the Lord your God with all your heart, soul, mind, and strength'; the second is like it: 'Love your neighbor as yourself.'" -- Jesus
"All things whatsoever that you wish men would do for you, do this for them. For this is the Law and the Prophets." -- Jesus
"Be merciful, as your Father in heaven is merciful. Judge not, and you shall not be judged; condemn not, and you shall not be condemned; forgive, and you shall be forgiven. ... With the same measure you use, it will be measured back to you." -- Jesus
"Love your enemies. Do good to those who hate you. Bless those who curse you. Pray for those who persecute you, that you may be children of your father in heaven. For he makes the sun to rise on the evil and on the good; he makes the rain to fall on the righteous and the unrighteous. If you love only those who love you, what credit is that to you? Even the worst sinners do that. If you greet only your brothers, what credit is that to you? Don't even the idolaters do that much? Be perfect, therefore, as your Father in heaven is perfect." -- Jesus
If we live this, then we'll have actually taught the terrorists a lesson.
Yes, I know, the sayings are paraphrased, and at places I have combined Luke's account and Matthew's account. What's the point of having more than one person's account of the same teachings unless we benefit from the knowledge of both?