I was recently in a discussion about Christian faith with a sceptic and, pushed hard in the debate, I played the 'good works card'. "Look at all the good things Christians have done over the years," I said.

"Ah," came the reply, "but humanists have done the same."

The response set me thinking. Do humanists do as much good as Christians?

Two caricatures must be dismissed at the start. Defenders of Christianity must reject any view that only they do good works while humanists and atheists do nothing. I'm happy to admit that there have always been humanists who have performed outstanding works of charity. On the other hand, advocates of Humanism must affirm that the Christian contribution to 'doing good' has been remarkable. One reason is the wide-ranging scope of the Christian response to human need. This I see being centred on two concepts: justice and righteousness. I would see justice as righting the wrongs in society and righteousness as doing good things; addressing life's negatives and affirming life's positives.

The Christian promotion of justice is reacting to a world that has an inbuilt tendency towards deceit, decay and darkness. Precisely because of this somewhat pessimistic view of things, Christianity has long battled against prejudice, corruption and cruelty. We may have, at times, fought those battles clumsily, but the world is a better place as a result.

If our role in standing for justice is somewhat negative, then the pursuit of righteousness is much more positive. Positive virtues ring out throughout the New Testament but let me quote the list from St Paul in Galatians 5: "the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control". It's a high standard and if we need to ask what a life with those characteristics might look like, then we have a 'worked example' in Jesus.

Built into the Christian faith is a powerful and comprehensive dynamic towards doing good. Of course anybody can conceive of a programme for dealing with what's wrong with the world. The problem is that good intentions are inadequate without motivation. Fortunately, Christianity supplies exactly that. For Christians the motive for good deeds is simply the gratitude we feel in response to God's grace in Christ. There is the expectation that we are to become progressively more like the Christ who redeemed us.

Most people prize societies where such virtues as honesty, liberty, tolerance and compassion are upheld, where goals such as democracy, education and gender equality are promoted, and where evils like poverty, cruelty and prejudice are deplored. But such values are not innate in the human psyche. While some may have been upheld by the Greeks and Romans for their elites, their emergence on any sort of society-wide scale is widely attributed to the impact of Christianity and the Bible. Book after book – some written by non-believers – affirm the importance of Christianity in the development of education, politics, science and healthcare. If you want specific examples, examine the epic battles of Christians in the 19th century against the evils of slavery, child labour, illiteracy and the abuse of the mentally ill. And remember organisations such as the YMCA, Red Cross, Samaritans, Salvation Army, Compassion and Tearfund, whose very names reveal their Christian origins.

But what of today? Surveys in both Britain and the United States show that Christians give more than those with no faith. A Barna Survey Report in 2013 on US giving noted that in the area of charity, Christians donated far more money than those who claimed no faith. A recent BBC survey also noted higher giving among religious believers than atheists in the UK.

So it seems to me that Christianity is inclined to do good works. I do not see that within Humanism. Indeed within humanist publications I find an awkward embarrassment that their followers are less generous and less committed to doing good than Christians. In fact some atheists, such as Alain de Botton, have been reduced to encouraging those who have 'moved beyond supernaturalism' to keep the best of religion, such as emphasis on service and giving.

The fact that so much of the world is in desperate need of assistance raises hard questions for both Christianity and Humanism about how we should respond in good works. For Humanism, it seems the overriding question is quite simply 'why?'. That is a question that we Christians need never ask. We, too, face a simple question about doing good works and one that is possibly more challenging: 'how?'.

Whether we are Christians or humanists, the saying 'people don't care how much we know, until they know how much we care' applies to us both.

Canon J.John is an evangelist, minister, speaker, social activist and writer. www.canonjjohn.com.