27 “But to you who are listening I say: Love your enemies, do good to those who hate you, 28 bless those who curse you, pray for those who mistreat you.29 If someone slaps you on one cheek, turn to them the other also. If someone takes your coat, do not withhold your shirt from them. 30 Give to everyone who asks you, and if anyone takes what belongs to you, do not demand it back.31 Do to others as you would have them do to you.
I cannot count the number of times these verses have been quoted by Christians and non-Christians, and almost always used to put Christians to shame.
They have chosen to disregard the other commandment, “thou shalt not kill”, which implies the sanctity of life, including our own lives not just the lives of our enemies.
We should therefore defend our lives if in danger as well as defend the lives of other people who are in danger.
Man is made in the image of God and therefore empires on earth can prevail only if God wills it, because they follow the natural laws God has imprinted in the hearts of man.
In similar fashion, civilised societies punish murderers, so God uses the civilised nations to punish wicked nations.
The crusades were a direct consequence of evil nations attacking the nations of God. They were defensive wars fought against the Muslims, who had been waging war against the Christians since the beginning of Islam in the 7th century. The Eastern Roman emperor had requested for help from the West against the Muslims, who had been attacking the Christian lands without avail.