The very existence of truth has been rejected by many people today, but the reality of an objective truth is a vital foundation for belief in God.

Have you ever tried to persuade someone to believe in Christ, only to be told, 'well, that's true for you, and I'm happy for you, but it's not true for me?'

This attitude is a new development in our societies, in which 'truth' is effectively seen as just an opinion rather than objective and real. In contrast, in times gone by, human beings tended to agree that there was a "truth" to be found, and searched hard to find it – often disagreeing vehemently along the way.

Perhaps this potential for conflict is the reason why the new belief that truth is 'just what an individual perceives it to be' has become so popular. It appears on the surface to be tolerant and accepting. We can't argue, fight, or wage wars on the basis of 'truth' if we just accept that there is no one truth to be found, and let people make their own minds up.

This is a foundation of modern, liberal, secular societies – they are supposed to allow for a plurality of beliefs with no strong imposition of values from the authorities, and so allow a person to be free.

Yet the reality of this new world of supposed tolerance is that our culture is now breeding some alarming extremism. In almost every political and social group, angry intolerance is spreading. Multicultural societies don't seem to be working well, as their different communities and groups become increasingly hostile to one another. There has been an increase in many other problems such as mental health, family breakdown, crime and other woes.

Christians often point to these troubles in society and argue that their own worldview, and the truths of the Christian faith, are the answer. There is a good case to be made. However, in a world that has rejected the notion of 'truth', we might first need to examine how and why the modern secular worldview has rejected truth, in order to then be able to argue in favour of Christianity.

The philosophical foundations of 'truth'

Although most people pay little attention to academic philosophical movements, the roots of the modern attitude lie in arcane intellectual discussions.

A movement that is called "postmodernism" has proved to be very influential. This is the source of a lot of the strange, modern ideas that are rapidly changing society, especially about biological sex and gender, and even about discussions related to the history of colonialism and racism. In a postmodern mindset, truth is not real but instead 'constructed' to serve the interests of the individual, often to claim or hold on to power, it is alleged.

Yet the reality is that these postmodern beliefs are therefore selling their own version of 'truth', and they seem just as keen to impose their own 'truth' onto others as other worldviews ever did – the intolerance of the recent upsurge in activist movements bears witness to this. In any case, it does not make sense to claim 'there is no truth', as it itself is a statement of truth.

Ignoring the problems that their own ideology creates - many postmodernists use their ideology to claim that Christianity was merely a means by which powerful people oppressed others, pointing to the era of Christendom when the religion did have a powerful influence on ruling authorities and atrocities were done in its name. They believe the claim of Karl Marx that religion is the 'opium of the people'.

These ideas are very ignorant of both Christian history and belief. For example, the reality is that the early Church had no power, was intensely persecuted by the powerful, and throughout history has been the means by which many oppressed people have been set free – both physically and spiritually. The New Testament is the stories of people with no worldly power other than what God gave them for the healing and liberation of others in their immediate surroundings. As Jesus said, his Kingdom is not of this world.

Even when Constantine converted and Christianity became the religion of the powerful Roman Empire, and it retained its power during the medieval period, the Church often acted to support the liberation of people. For example, slavery was outlawed in Europe during the Middle Ages due to the persuasion of people like Pope Gregory I and Anselm of Canterbury. Although European countries were complicit in the new slave trade to the Americas for a period of time, it was a group of devout Christians such as William Wilberforce who put an end to this travesty.

In other situations where the Church is accused of being complicit in evil, such as in Nazi Germany, many Christians spoke and acted against the regime at great risk to themselves, such as the Bishop of Munster Clemens von Galen, whose public speeches were the reason the despicable regime was forced to end its mass slaughter of people with learning disabilities.

There were many heroes who hid Jewish people and helped them to hide from certain death, such as devout spinster Corrie ten Boom, the villagers of Le Chambon and their pastor Andre Trocme, Monsignor Hugh O'Flaherty and orthodox nun Mother Maria Skobtsova. These are all inspiring examples of how Christian faith inspires its holder to liberate the oppressed from the powerful through works of love.

But the reason the Church did act in favour of the oppressed in this way was because they believed a truth – the reality of God and the morals that He instituted, such as the intrinsic value of human life. These heroes did not adopt these truths to have power over others, as postmodernists claim, but instead they saw the beauty, goodness, love, freedom and truth of Jesus Christ, and sought to live that out in their daily lives to help others to escape evil and discover the same divine reality, both spiritually and physically.

So what is truth?

According to the Stanford Encyclopedia of Philosophy, "truth is one of the central subjects in philosophy. It is also one of the largest. Truth has been a topic of discussion in its own right for thousands of years."

Because many of these academic discussions took place within Christian societies, there is a huge amount of Christian influence on the philosophical debate, such as the thoughts of the great medieval thinker Thomas Aquinas, for whom the existence of truth was very real.

However a Christian understanding of truth began to be questioned by atheistic philosophers in later centuries, which accelerated in the 19th Century, when Friedrich Schleiermacher questioned the historicity of the Bible, Charles Darwin doubted the Creation story, and Friedrich Nietzsche said "truths are illusions which we have forgotten are illusions," doubting that God exists or that there is any real meaning or purpose in the world.

Then in the 20th Century, philosophers increasingly questioned the relationship between language, mind and reality, leading to postmodern thought. But perhaps this was more to do with the rise of atheistic ideas? If it is true that there is no God, and that all that exists is the material world and what we can surmise about it through science, then truth becomes a much more debatable concept.

Yet most people can see intuitively that there is more to life than just the material world of atoms, molecules and scientific laws. Deep inside, we know we have a soul and that there is meaning in the world – indeed when someone does lose this sense, it is often accompanied by great grief and distress.

The evidence in an ordinary life is overwhelming: the feeling of love when you hold a newborn in your arms; the incredible beauty of nature or an exquisite work of art of music; the experience of the love of God in many conversions; even the reality of mathematical and scientific equations, which have been said by many scientists to point to God himself. These all reflect the reality that is beyond our material world.

And Jesus explicitly addressed the existence of truth with some powerful statements: "I am the way, the truth, and the life" (John 14:6) and "If you hold to my teaching, you are really my disciples. Then you will know the truth, and the truth will set you free" (John 8:32). In total, there are 137 Bible verses that refer to truth.

For those who know that God is real, it is easy to believe in a 'truth' that exists over and above the material, physical world. God is the source of truth, and what truth is grounded in.

We can still be humble and tolerant and recognise that our own human frailties mean that we can be deceived, and that we should listen to the opinions of others with respect and without force. But that does not mean we should ever need to abandon the reality that there is a real, objective and important truth to be found, and that it is based on the One who told us that he is 'the Truth'.

Heather Tomlinson is a freelance Christian writer. Find more of her work at https://heathertomlinson.substack.com/ or via X (twitter) @heathertomli