Most people who identify as Christian are nominal Chrisitians, they don't actively participate in religion.
Christianity is declining in the USA and Australia too.
https://www.newsweek.com/christianity-dying-religion-millennials-europe-859272 Quote: Christianity Is a Dying Religion for Millennials in Europe
BY CRISTINA MAZA ON 3/23/18 AT 4:13 PM EDT
Europe's youth don't practice Christianity anymore, according to a new European social survey.
The Continent was once the home of the majority of the world's Christians, but today many people between the ages of 16 and 29 claim they have no religious affiliation. In general, a high percentage of young people throughout Europe never attend religious services, never pray and don't identify with any religious group. In fact, there are only three countries in Europe where more than one in 10 young people said they attend a religious service weekly: Poland, Portugal and Ireland.
Young people in the Czech Republic are the least religious of all, according to the survey. A full 91 percent of young people from the formerly communist country say they don't identify with any religion, and 70 percent said they never attend a religious service. In countries like Estonia, Sweden and the Netherlands, between 70 and 80 percent of all young people say they have no religious affiliation.
"Overall, in 12 out of our 22 countries, over half of young adults claim not to identify with any particular religion or denomination," the report, authored by London's Benedict XVI Center for Religion and Society at St. Mary's University in the United Kingdom reads. "In 19 of them, over a third do."
The data reflects an ongoing trend among the overall population. In 1910, over 66 percent of the world's Christians lived in Europe, according to the Pew Research Center. In 2010, that percentage had shrunk to a little under 26 percent.
That doesn't mean the number of Christians worldwide has dropped during that period. In fact, the number of Christians worldwide quadrupled in those 100 years. A 2011 demographic study of more than 200 countries revealed that there are 2.18 billion Christians of all ages scattered across the globe. Around a third of the world's roughly 7 billion inhabitants are Christian. But by 2010, Christians were spread out more evenly across the Americas, Europe, Africa and Asia.
Some countries in Europe, however, are holding on to their Christian faith more than others. The most religious countries in Europe are Ireland, Lithuania and Poland. In Poland, for example, only 17 percent of young people do not identify with a religion. Around 47 percent of young Poles attend mass every week.