Historically, Portugal has been a country of Catholics. The 2021 census demonstrated that this trend has not been inverted, as over 80 percent of the population in Portugal identified as Catholic. Protestant or Evangelic believers accounted for more than two percent of the population, while Jehovah's Witnesses constituted one percent of residents. Among non-Christian faiths, Muslims were the most representative group, making up 0.42 percent of the population.

Religious but generally not practicing the faith

In the same year, Catholics numbered more than seven million people spread throughout the country, conquering the religious majority in the mainland and in the two autonomous regions. Citizens without religion totaled more than 1.2 million, which made of them the second most numerous religious group in Portugal. Young people presented the same religious trend, with young Catholics being the most representative group, followed by non-religious. Among youngsters, the attendance of religious events was mostly conducted occasionally, while a quarter did not participate in such proceedings at all.

The contribute of immigration to the growth of Evangelical Christianity

Despite being the minority, non-Catholic Christian and non-Christian faiths have been growing in Portugal. In 2011, Evangelical believers totaled 75.6 thousand, more than doubling ten years after. Such growth was partially motivated by the increase in Brazilian immigration, as more than 61 percent of new members of Evangelical churches in 2023 were of Brazilian origin. In fact, Brazil was the place of origin of almost 82 percent of all the immigrant Evangelical Christians residing in Portugal. However, more than a quarter of new Evangelical Christians were Portuguese, which shows that other religions, namely Christian Catholicism, have been losing members to Evangelical Catholicism.

The 2021 census showed that, out of almost 8.8 million residents in Portugal aged 15 years and more, over seven million were catholic. The second most representative religious group in the country was protestant, a community with almost 187 thousand members. Islam accounted for almost 36.5 thousand believers, while Judaism for just 2.9 thousand. Those without religion totaled 1.2 million residents.

This statistic shows the estimated Muslim share of the population in different European countries as of 2016. With a Muslim population that makes up around a quarter of it's population, Cyprus has the highest estimated share of Muslims living in its borders. The Muslim share of the Bulgarian and French populations is also quite high with 11.1 and 8.8 percent shares respectively. Portugal, Romania, Czechia and Poland have the lowest Muslim shares of the population at under one percent.

Portugal: Shia Muslims as percent of the total population: The latest value from is percent, unavailable from percent in . In comparison, the world average is 0.0 percent, based on data from countries. Historically, the average for Portugal from to is percent. The minimum value, percent, was reached in while the maximum of percent was recorded in .

Portugal: Muslims as percent of the total population: Pour cet indicateur, The Cline Center for Democracy fournit des données pour la Portugal de 1960 à 2013. La valeur moyenne pour Portugal pendant cette période était de 0 pour cent avec un minimum de 0 pour cent en 1960 et un maximum de 0 pour cent en 1960.

Portugal: Sunni Muslims as percent of the total population: Pour cet indicateur, The Cline Center for Democracy fournit des données pour la Portugal de à . La valeur moyenne pour Portugal pendant cette période était de pour cent avec un minimum de pour cent en et un maximum de pour cent en .

Portugal: Shia Muslims as percent of the total population: Pour cet indicateur, The Cline Center for Democracy fournit des données pour la Portugal de à . La valeur moyenne pour Portugal pendant cette période était de pour cent avec un minimum de pour cent en et un maximum de pour cent en .

In around 716 AD, the city of Santarém, Portugal, was conquered by the Berber and Arab armies that swept the Iberian Peninsula and went on to rule the region until the 12th century. Archaeological excavations in 2007/08 discovered an Islamic necropolis (Avenida 5 de Outubro #2–8) that appears to contain the remains of an early Muslim population in Santarém (8th– 10th century). In this study, skeletal material from 58 adult individuals was analysed for stable carbon (δ13Ccol; δ13Cap), nitrogen (δ15N) and sulphur (δ34S) isotope ratios in bones, and stable oxygen (δ18O), carbon (δ13Cen) and radiogenic strontium (87Sr/86Sr) isotopes in tooth enamel. The results of this study revealed a dietary pattern of predominantly C3-plant and domestic C3-fed herbivore consumption during adulthood (δ13Ccol and δ15N, respectively) but a higher proportion of C4-plant input during childhood (δ13Cen) for some individuals—interpreted as possible childhood consumption of millet porridge, a common practice in North Africa—in those with unorthodox burial types (Groups 1 and 2) that was not practiced in the individuals with canonical burials (Group 3). In this first mobility study of a medieval Muslim population in Portugal, δ18ODW values revealed greater heterogeneity in Groups 1 and 2, consistent with diverse origins, some in more humid regions than Santarém when compared to regional precipitation δ18O data, contrasting the more homogenous Group 3, consistent with the local precipitation δ18O range. Ancient DNA analysis conducted on three individuals revealed maternal (mtDNA) and paternal (Y-chromosome) lineages compatible with a North African origin for (at least) some of the individuals. Additionally, mobility of females in this population was higher than males, potentially resulting from a patrilocal social system, practiced in Berber and Arab communities. These results serve to offer a more detailed insight into the ancestry and cultural practices of early Muslim populations in Iberia.

In around 716 AD, the city of Santarém, Portugal, was conquered by the Berber and Arab armies that swept the Iberian Peninsula and went on to rule the region until the 12th century. Archaeological excavations in 2007/08 discovered an Islamic necropolis (Avenida 5 de Outubro #2–8) that appears to contain the remains of an early Muslim population in Santarém (8th– 10th century). In this study, skeletal material from 58 adult individuals was analysed for stable carbon (δ13Ccol; δ13Cap), nitrogen (δ15N) and sulphur (δ34S) isotope ratios in bones, and stable oxygen (δ18O), carbon (δ13Cen) and radiogenic strontium (87Sr/86Sr) isotopes in tooth enamel. The results of this study revealed a dietary pattern of predominantly C3-plant and domestic C3-fed herbivore consumption during adulthood (δ13Ccol and δ15N, respectively) but a higher proportion of C4-plant input during childhood (δ13Cen) for some individuals—interpreted as possible childhood consumption of millet porridge, a common practice in North Africa—in those with unorthodox burial types (Groups 1 and 2) that was not practiced in the individuals with canonical burials (Group 3). In this first mobility study of a medieval Muslim population in Portugal, δ18ODW values revealed greater heterogeneity in Groups 1 and 2, consistent with diverse origins, some in more humid regions than Santarém when compared to regional precipitation δ18O data, contrasting the more homogenous Group 3, consistent with the local precipitation δ18O range. Ancient DNA analysis conducted on three individuals revealed maternal (mtDNA) and paternal (Y-chromosome) lineages compatible with a North African origin for (at least) some of the individuals. Additionally, mobility of females in this population was higher than males, potentially resulting from a patrilocal social system, practiced in Berber and Arab communities. These results serve to offer a more detailed insight into the ancestry and cultural practices of early Muslim populations in Iberia.

In 1498, Vasco da Gama became the first known European to sail to India by circumventing Africa, which ushered in a new age of European sea trade with Asia. Initially, Indian rulers were unimpressed and wary of the Portuguese, and Muslim traders in the region were hostile, but the Portuguese were able to assess what could be traded for exotic goods (mostly spices) and lucrative trade routes were established after subsequent journeys. Additionally, the Portuguese quickly learned that they had the technological advantage in conflict, and repelled attacks from their Muslim rivals. Fortified trading posts, known as factories, were then established along the African and Asian coasts to protect these trade routes, and these became the foundation upon which the Portuguese Empire (Europe's longest-lasting) was built.

Colonization and competition In 1494, the Treaty of Tordesillas saw Portugal and Spain draw a line through the Atlantic, with each crown laying claim to all non-Christian lands on their respective side. No other European power acknowledged these claims, but it would take almost a century for the British, Dutch, or French to begin establishing their own maritime empires; this meant that the Portuguese had a near-monopoly on the Indian spice trade for almost 100 years, and this was the century when their trade with Asia was most active. Portuguese traders not only did business with merchants in India, but they also explored further, and established trade routes with present-day China, Indonesia, and Japan, and even facilitated trade between these cultures. In the 1590s, the Dutch then followed the Portuguese model of empire building and quickly emerged as Portugal's biggest rival in Asia. VOC The Dutch and Portuguese were in conflict for over 60 years, across four continents, and the Asian and African conflicts are often referred to as the "Spice War". The Netherlands eventually usurped Portugal as the strongest European trading power in Asia by the mid-1600s. Most of the Dutch trade was done through the Dutch East India Company (VOC), which is often considered the most valuable company to have ever existed. In the 17th century, 56 percent of all ships that travelled from the given countries to Asia were Dutch, and the figure was over 44 percent in the following century. Such companies were not only trading enterprises, but also acted in the military and political interests of their respective crowns. The VOC went into decline in the mid-1700s, as the British Empire gained the upper hand in its rivalry with the Netherlands. The British East India Company then consolidated its power on the Indian subcontinent, and Dutch interests were largely centered in the East Indies (present-day Indonesia), which remained a Dutch colony until the Second World War. For France, its primary colonial power in Asia was in French Indochina, made up of present-day Cambodia, Laos, and Vietnam, although the seven European powers had trade connections all over Asia, and all competed or cooperated with one another at various points in these 300 years.