The origin of the Reformation is generally considered to date back to the publication in Germany of the Martin Luther’s 95 Theses on October 31, 1517. Most of these opposed the practice of selling indulgences (reducing the time spent in purgatory because of sin) to finance the construction of St Peter’s Basilica.
Protestantism arrived in Switzerland very early on (around 1520). The two most prominent reformers were Ulrich Zwingli (Zurich) and Jean Calvin (Geneva).
The Reformation spread mainly in urban areas (Basel, Bern, Geneva, Zurich) and was also sometimes imposed militarily, for example with the annexation by the Bernese of the Duchy of Savoy lands.
The share of Protestants, who used to be the majority in Switzerland, has fallen sharply in recent decades, notably in favour of those who declare themselves non-religious. The share of Catholics has stayed more or less stable, in particular due to the massive influx of immigrants from Italy, Spain and Portugal.
According to 2015 figuresexternal link from the Federal Statistical Office, Catholics are the majority in Switzerland, with 38% of the population. The mainstream Protestant church represents 26%, Islam nearly 5%. More than 23% have no religious affiliation, compared with only 1% in 1970.