Globally, the Church is thriving. Thousands are coming to faith daily in China, parts of Africa and South America. Yet here in Europe the story is one of decline. There are bright spots amid that decline, but still the overall trend is toward a reduction in the number of believers, both committed and nominal.

In the US, some feel that the precedent set by Europe is one which America will follow in due course.

Into this mix, this morning we reported that the number of adherents to the Church of Sweden is in free fall. 86,000 members of the Church left in 2016 – the highest number ever in a single year. A similar pattern has emerged in Norway.

In both these countries, the official state Church has been disestablished after hundreds of years. In 2000, Sweden's Church separated formally from the state, while January 1 this year saw the same thing happen in Norway. Across the bridge in Denmark, the state Church remains officially established. Yet the same reason which has seen many thousands of nominal Norwegians and Swedes officially sever their links with the Church is at play there too. To avoid paying the Church tax – a levy which supports the work of the Church – people who are officially members, even if they rarely attend, are leaving. After an atheist advertising campaign, over 10,000 people decided to leave the Danish Church earlier this year.

Finland has a similar story to tell, of high institutional membership, but low levels of participation. There, though, there are interesting signs of a reawakening of belief.

On the whole, though, projections suggest the decline in numbers of the official (and formerly official) state Churches of Europe may continue for decades to come.

It leads to the question which has been asked repeatedly in the US and the UK over generations – what use is a state Church?

In the USA, there has never been an officially established national Church. However, some states did have official Churches. By 1833, though, the final official links between the Congregational Church and the State of Massachusetts had been severed. This means that for most of its history, the US has been a 'Christian country' (demographically, Christian faith was the biggest religion, Judeo-Christian values were the basis of much of the law and culture etc.) without having an established Church.

In Great Britain, we have a very different history. The Church in Wales was disestablished in 1926, but both England and Scotland retain their established Churches to this day. Constitutionally, the Church still plays a central role in British life. Prayers are said in Parliament at the start of each day, Bishops still sit in the House of Lords by right and the Queen remains the Supreme Governor of the Church of England.

Significantly, the system in England and Scotland works differently from elsewhere in Northern Europe. There is no Church tax here, so there is no financial incentive to leave. In fact, it is tricky to know what membership actually entails. One in 10 infants are still baptised in the Church of England, but figures show that only around 750,000 people are regular attenders at church – something like 1.5 per cent of the population. There is no obvious way to 'leave' the Church of England either, unlike in Norway where an online system allowed people to opt out.

With there being no change likely in Great Britain in the near future, Christians in the UK and US live with very different systems. But what are the advantages and disadvantages of the two systems?

The USA, free of the encumbrance of state religion, has a vibrant and thriving Christian Church. Because many flowers were allowed to bloom, there have been a wide variety of movements. Some of them have been inspirational, such as Pentecostalism, while others have been considered heretical – Jehovah's Witnesses, Mormons and Christian Science, for example.

The entrepreneurialism of American Protestantism has led to great dynamism and the experience of the Great Awakenings, which transformed the religious landscape of the country would undoubtedly have been different had there been an established Church. Yet that dynamism has led to overreach. The excesses of the prosperity gospel and the exploitative end of televangelism were also partially a fruit of the free-market in religious ideas.

How about the other side of the pond? England's and Scotland's established Churches and their closeness to the political and cultural elite have insulated the UK from the more extreme expressions of political Christianity that have proved so divisive in America. The British equivalent of the Religious Right has happily remained marginal for this reason.

Yet, it also seems that some of the dynamism that characterises American Christianity has been lacking in the UK. We have certainly had revivals, from Wesley's Methodist movement to the pit villages of South Wales in the early 20^th century. But to many Brits, the default version of Christianity they have been offered is a more 'woolly' version of established Anglicanism. Having said that, there is vibrancy to much of the Church of England still – and its establishment does make it visible to many non churchgoers who still feel a sense of ownership of 'their' parish church.

Is establishment or disestablishment preferable, then? There are arguments for both. It's a question made even more interesting when looking at China, which has a state-sanctioned (though not officially linked) Church and various underground networks, too, and where much of the future shape of Christianity will be decided.

Should we agree with Danish theologian and philosopher Soren Kierkegaard, who described the established Church as, "from the Christian point of view, an impudent indecency"?

Ultimately, there probably isn't a 'right' answer as such, unless you are a thoroughly committed secularist or Nonconformist. In the US and UK, there is little state interference with the Church and that is as it should be. Sadly, elsewhere, authoritarian regimes such as China do regulate how the official Churches can behave. The Church is at its best when it is committed to the Gospel – helping as many people as possible to love God and neighbour. This can, and does, happen in both established and other Churches. It's that we should be focused on.