Values such as tolerance, charity and human rights are often considered secular beliefs of the modern world, independent from any religion, especially the Christian faith that once infused the countries where these values were born.

But one historian realised this was false as he was perusing the stories and documents of the ancient world. Tom Holland, the bestselling author of books such as Rubicon, had abandoned his own childhood faith. However, as he read more of the works of history, he realised that the modern values we all take for granted had a particular inspiration: Christianity, and especially the message of the Cross.

He gives painstaking details of these developments in his 2019 book Dominion: the making of the Western mind (in the US, it was subtitled How the Christian Revolution Remade the World). It proved very popular with Christians.

Soon after the book was first released, the late Reformed pastor Tim Keller wrote for The Gospel Coalition: "It is hard to overstate the importance of Holland's book ... Christianity has such an enduring, pervasive influence that we cannot condemn the church for its failures without invoking Christian teaching and beliefs to do so."

Here are just some of our modern ethics that came from the Gospel message, according to Holland:

Slavery is wrong

Most Christians are aware that the 18th Century movement to abolish the slave trade in England was driven by a group of Evangelical Protestants called the Clapham Sect, the most famous being William Wilberforce. In the agreement between European powers to outlaw the slave trade in 1815, "the language of evangelical protestantism was fused with that of the French Revolution," Holland explains.

It had taken time for European laws to be applied to people from other continents, but long before that, there had been another anti-slavery battle that was started and won by the church. Slavery in Europe itself had been outlawed for a long time before that. Theologian Gregory of Nyssa was the first to argue in the 4th Century that slavery itself was intrinsically sinful.

Weakness is greatness

In the Roman world that Christianity was born into, and in most civilisations throughout history, the weak and vulnerable were despised. A central theme in Holland's work is that Christianity promoted the direct opposite of this, through its humble Servant King, hung on a Cross. It is this aspect of Christianity that has been scorned by its haters like Friedrich Nietzsche, the Nazis, and first of all by the Romans and the ancient world.

"Divinity, then, was for the very greatest of the great: for victors, heroes, and kings," writes Holland. "Its measure was the power to torture one's enemies, not to suffer it oneself: to nail them to the rocks of a mountain, or to turn them into spiders, or to blind and crucify them after conquering the world. That a man who had himself been crucified might be hailed as a god could not help but be seen by people everywhere across the Roman world as scandalous, obscene, grotesque."

The church has been aware of this since its beginning: St Paul outlined the "foolishness" of the crucified God in 1 Corinthians 1, saying in verses 27-28: "God chose the foolish things of the world to shame the wise; God chose the weak things of the world to shame the strong. God chose the lowly things of this world and the despised things—and the things that are not—to nullify the things that are, so that no one may boast before him."

Humans have rights

The modern movements for human rights can sometimes be hostile to Christianity. It wasn't always so.

"That every human being possessed an equal dignity was not remotely self-evident a truth," states Holland in Dominion. "A Roman would have laughed at it. To campaign against discrimination on the grounds of gender or sexuality, however, was to depend on large numbers of people sharing in a common assumption: that everyone possessed an inherent worth. The origins of this principle—as Nietzsche had so contemptuously pointed out—lay not in the French Revolution, nor in the Declaration of Independence, nor in the Enlightenment, but in the Bible."

Sexual desires should be restrained

Holland describes the shocking dominant morals of Roman society – rich and powerful men using slaves, women and anyone they deemed inferior for their own lust. "As captured cities were to the swords of the legions, so the bodies of those used sexually were to the Roman man," he wrote.

He perceives the traditional ethic of sex being exclusively within monogamous marriage to be the fruit of Christendom.

The poor and vulnerable should be helped

it is taken to be self-evident within Christian societies that charity work, welfare and support for the poor and vulnerable is inherently good. But it wasn't always so. The heroes of the ancient world had no pity for the less able. Holland summarises: "The starving deserved no sympathy. Beggars were best rounded up and deported. Pity risked undermining a wise man's self-control. Only fellow citizens of good character who, through no fault of their own, had fallen on evil days might conceivably merit assistance."

Helping the poor is a virtue that is assumed to be good in the modern world, and the historian credits this to Christianity.

Romantic love

In history and still in many cultures today, marriage was about preserving the extended family and status and a decision made by the older relatives, not the individuals getting married. Holland credits the change in this to Christianity: "Opening up before the Christian people was the path to a radical new conception of marriage: one founded on mutual attraction, on love. Inexorably, the rights of the individual were coming to trump those of family."

These are just some of the insights in Holland's sweeping overview of the reach of Christendom, which is a powerful and enthralling read.