PARIS: As the piano strikes up, the congregation sways, palms to the ceiling, fists in the air, murmurs of hallelujah punctuating the music. Pastor Franck Lefillatre, besuited and bathed in the spotlight on his podium, intones into a microphone.

“Let out the words that are in your heart,” he urges. His whispers crescendo to booming rhetoric. Behind him, emblazoned in gold lettering, are the words: “Jesus Christ: the same yesterday, today, eternally.”

As evangelical services go, this gathering on a rainy Sunday afternoon is nothing unusual. In countless churches around the United States and many other countries it would be a staple means of Christian worship.

But this is not the American Bible belt. It is the Church of Paris-Bastille, and this congregation is just one of a growing number of evangelical communities spreading through France and prospering in spite of its staunchly secular - and Catholic - traditions. From a postwar population of around 50,000, French evangelicals are now estimated to number between 450,000 and 500,000. According to the Evangelical Federation of France (FEF), the number of churches has risen from 800 in 1970 to more than 2,200 today.

This week the boom made headlines when thousands of evangelicals - who are estimated to make up two-thirds of the country’s practising Protestants - descended on Strasbourg to turn the 500th anniversary of Calvin’s birth into a huge, media-covered event. It was not something even the most hopeful of believers could have prayed for.

For Lefillatre, whose church is part of the World Assemblies of God Fellowship, the largest global Pentecostal denomination, the growth is reflected within the bare, shabby walls of the Paris-Bastille. In the three years he has been pastor there, he said, the congregation has gone from around 250 to 350 or 400. Do they come every so often or without fail every Sunday? “Every Sunday,” he said firmly.

On paper France would seem one of the least likely places for this branch of Christianity to gain a foothold. For centuries, Protestantism was the embattled minority in a country Catholics liked to call the “eldest daughter of the church” because of its strong ties to Rome.

More importantly, though, ever since France harnessed popular discontent with the influence of Catholicism and wrote a separation of church and state into the constitution, the French republic has worshipped at the altar of laicite - the concept of a secular state. The gradual emergence of evangelicals as a force has, therefore, raised eyebrows.