For people of my age, part of the musical score to our lives is the sound of Joan Baez singing the classic protest song 'We shall overcome.'

This song, which has been sung by numerous artists other than Baez, has come to feature as the chosen anthem of protest movements around the world. In the 1940s and 50s the song began to be sung in American trades union circles and in the 1960s it was picked up and widely used by the American Civil Rights movement.

From then on it became a universal protest song, being adopted, for example, by anti-Apartheid protesters in South Africa, by the Catholic Civil Rights movement in Northern Ireland, by those involved in Bangladesh's war of independence in 1971 and by those protesting against the communist government in Czechoslovakia in 1989.

In 2010 a new version was issued as a protest against the Israeli blockade of Gaza and in 2012 Bruce Springsteen performed the song at the memorial concert in Oslo for the victims of the terror attacks by Anders Breivik the previous year.

Although this song has been adopted by those of all faiths and none, it is a song that is Christian in origin. There is a continuing debate about who was the original author of the song, with the two possible candidates being the Black American Methodist minister Charles Tindley and the Black American Baptist choir director Louise Shropshire.

At the moment Shropshire seems the more likely candidate, but either way the song was originally written by a Christian and it is only when the song is understood in Christian terms that the affirmations contained in its lyrics fully make sense.

The basic affirmation made in the lyrics is, of course, the affirmation that 'we shall overcome.' Alongside this basic affirmation there are four others, 'we'll walk hand in hand,' 'we shall live in peace,' 'we shall all be free' and 'we are not afraid.'

The way that the song works is that the affirmations 'we'll walk hand in hand,' 'we shall live in peace' and 'we shall all be free' give content to the affirmation 'we shall overcome' and the belief that these affirmations are true explains why 'we are not afraid.'

What the song proclaims, then, is a belief in the coming of brotherhood, peace and freedom. These are things which many, if not all, people are looking for and that is why the song has become so popular. It affirms what millions of people would like to believe, that a better world is possible.

However, if we set aside a Christian perspective for a moment and just look at the evidence of history, the indications that the better world envisaged in the song is possible are strictly limited. It is true that changes for the better do take place. The American civil rights movement and the campaign against apartheid led to the removal of racist laws in the United States and South Africa. The institutional bias against Roman Catholics in Northern Ireland has been corrected. Bangladesh achieved its freedom from Pakistan and the communist government of Czechoslovakia was overthrown.

However, none of these changes, or any other parallel changes, such as the overthrow of oppressive Arab governments in the so-called 'Arab Spring,' have been unequivocally successful in bringing about brotherhood, peace and freedom.

In spite of the successes of the civil rights movement there are still large amounts of racial division and inequality in the United States. Post-apartheid South Africa is still a racially and economically divided society and it also has an extremely high rate of violent crime.

Sectarian divisions continue to exist in Northern Ireland. Bangladesh remains an extremely poor country with significant political problems. And major economic, political and social problems remain in Eastern Europe thirty-four years after the collapse of the old communist bloc.

Furthermore, it is not simply a case of the trajectory of history not moving towards brotherhood, peace and freedom as fast or as comprehensively as we might like. As the example of places such as Somalia, the Democratic Republic of Congo, Ukraine and now Israel and Gaza show, the movement of history can and does move away from brotherhood, peace and freedom.

If we now bring in a Christian perspective, we find that none of this is surprising. God has created all human beings with an inherent sense of right and wrong and this, together with the influence, whether direct or indirect, of the Christian belief in the importance of brotherhood, peace and freedom and the work of the Holy Spirit in people's hearts explains why movements towards beneficial change continue to take place.

What the Christian faith also tells us is why things continually go wrong. The biblical narrative tells us that the very first human beings chose to disobey God (Genesis 3). The results of this original transgression have then been passed on down the generations with the result that every human being is a sinner who not only has a broken relationship with God, but also a broken relationship with all other human beings and with the rest of creation.

As a result of what Article IX of the Thirty Nine Articles calls this 'fault and corruption of the nature of every man that is naturally engendered of the offspring of Adam' human beings constantly lack the wisdom to know what they should do, or the desire to do it, or both, and the result of this multiplied down the generations explains why human beings face such intractable problems and why movements to make things better always only have limited effect. Christians are not surprised (or at least should not be) when things go wrong. It is what their faith tells them will happen.

Given that this is the case, why is it possible for a Christian to write a song that declares 'we shall overcome' and why is it possible for Christians to go on singing it? The answer is because Christians also believe that sin will not have the last word in the human story. The Bible tells us that God promised to bring about universal blessing through the descendants of Abraham (Genesis 12:3) and that God further promised that the result of this blessing would be a situation of universal peace, happiness and freedom:

'It shall come to pass in the latter days that the mountain of the house of the LORD shall be established as the highest of the mountains, and shall be raised up above the hills; and peoples shall flow to it, and many nations shall come, and say: "Come, let us go up to the mountain of the LORD, to the house of the God of Jacob; that he may teach us his ways and we may walk in his paths." For out of Zion shall go forth the law, and the word of the LORD from Jerusalem. He shall judge between many peoples, and shall decide for strong nations afar off; and they shall beat their swords into ploughshares, and their spears into pruning hooks; nation shall not lift up sword against nation, neither shall they learn war anymore; but they shall sit every man under his vine and under his fig tree, and none shall make them afraid; for the mouth of the LORD of hosts has spoken.' (Micah 4:1-4)

These promises were made good when God took human nature upon himself in the person of Jesus Christ and through his life, death and resurrection undid the results of the fall of the first human beings (Romans 5:12-21, 1 Corinthians 15:20-28). The effects of this are already being felt in history as Christians living in renewed obedience to God act to make things better and they will be finally and definitively revealed when Christ returns in glory to establish the new Jerusalem spoken of in Micah and to bring about a universal reign of brotherhood, peace and freedom that will endure forever (Revelation 21:1-22:5).

It is because Christians believe this that they can go on singing 'we shall overcome.' It is because Christians believe this that they can affirm 'we'll walk hand in hand', 'we shall live in peace' and 'we shall all be free'. It is because Christians believe this that they can look at all the bad things that happen in their own lives and in the life of the world and still declare 'we are not afraid.' As St. Paul put it in Romans 8:31-39:

'If God is for us, who is against us? He who did not spare his own Son but gave him up for us all, will he not also give us all things with him? Who shall bring any charge against God's elect? It is God who justifies; who is to condemn? Is it Christ Jesus, who died, yes, who was raised from the dead, who is at the right hand of God, who indeed intercedes for us? Who shall separate us from the love of Christ? Shall tribulation, or distress, or persecution, or famine, or nakedness, or peril, or sword? As it is written, "For thy sake we are being killed all the day long; we are regarded as sheep to be slaughtered." No, in all these things we are more than conquerors through him who loved us. For I am sure that neither death, nor life, nor angels, nor principalities, nor things present, nor things to come, nor powers, nor height, nor depth, nor anything else in all creation, will be able to separate us from the love of God in Christ Jesus our Lord.'

Oh, deep in my heart, I do believe we shall overcome, some day. As Tolkien put it in The Lord of the Rings a day is coming when 'everything sad is going to come untrue.'

Martin Davie is a lay Anglican theologian and Associate Tutor in Doctrine at Wycliffe Hall, Oxford.