The first recording of any religion in the commonwealth can be dated to 1739, to the founding of the country. Felix Barbone, the Italian-Finnish explorer who discovered the land and would eventually have it named after him, was an Evangelical Lutheran, as were many of his followers. New Gothenburg (later to be named Barbone Landing), their settlement and the first town to be constructed in the fledging new Swedish colony, had the First Evangelical Church of New Gothenburg constructed in 1741. The church remained a popular tourist destination until a fire destroyed it in 1976, allegedly set by a radical neo-pagan. A new church was built on the site the following year.
In 1797, the Barboneia Evankelis-Luterilainen Kirkko, or Evangelical Lutheran Church of Barboneia, was founded and united the various Lutherans across the still relatively new country together. Often seen as the (somewhat) more liberal choice of religion compared to Eastern Orthodoxy and Judaism in Barboneia. The church has no outspoken beliefs against same sex marriage, transsexuality, abortion, and other such issues, but is known for a rather odd yet serious hatred against polygamists. This stems from the time of the leadership of Sakari Ojala, the presiding bishop of the church in 1868. Supposedly, he was a serial polygamist, having five wives at once, and wanted to try and change the tenements of the church so that polygamy was required for membership. He was ousted from power after much outrage.
The other largest Christian sect in the nation is the Pyhän Itäinen Ortodoksinen Katolinen Kirkko Barboneia, or the Holy Eastern Orthodox Church of Barboneia. It is quite larger than the Evangelical Lutheran Church, and is considered the more "traditionalist" Christian institute in the country. It was founded in 1823 following a large immigration of Russian and other Eastern European ethnic groups to Barboneia. The first Eastern Orthodox cathedral, Saint Augustine's Cathedral, was built in Talecton in 1829 and remains a popular tourist site in the city to this day. In recent years, the church's popularity has declined following statements from presiding bishop Lars Mäkeläinen in 2014 that denounced "sinful" acts such homosexuality and abortion. Despite turning off many members of the younger generation, the Eastern Orthodox Church remains the largest Christian sect in the country.
Judaism did not truly exist in Barboneia until the late 1800s, when the first Jewish synagogue in the country was founded in Alakuloinen, Central Barboneia. Jews had lived in Barboneia since its founding, but it was not until 1895 that it truly began to grow, causing a new generation of Barboneia Juutalaiset to be introduced into the mainstream society. Unlike many European nations, Jews were not discriminated against and were happily accepted as good, lawful Barboneian citizens. Of course, stereotypes existed, but the Jewish population was more inclined to laugh them off rather than become offended. During the Second World War, many Jews managed to flee from Germany to Barboneia thanks to a governmental agreement between the countries. Barboneia, a neutral country during the conflict, offered to provide resources to the Nazi war machine if the Germans in turn allowed some Jews to immigrate there. This ended up saving the lives of many Jewish Germans who would've otherwise ended up being killed in the Holocaust, and helped to bolster the Jewish population in Barboneia, but the agreement also grew ire from the allied countries, as Barboneia had basically helped support Germany during the war. As such, Barboneia was forced to pay minor reparations following the war.
Other religions manage to exist in the country, as evidenced by census statistics, but they are often overlooked. They include Buddhism, Hinduism, Islam, and countless others. However, they are vastly outnumbered by the number of irreligious people in the nation. It just seems that, to about 20% of Barboneians, religion is unpopular.
In short, Barboneia is diverse when it comes to people who do, and don't, believe in a higher power. But no matter what someone may or may not believe in, they can find comfort in knowing that the government of Barboneia discriminates against no one regardless of religion.