Dutch and English are common second languages in Indonesia, but primarily only university-educated people speak these languages with any fluency. In business and tourism these languages are widely spoken as are other popular international languages, but in much smaller numbers.
Religion
About 85% of Indonesia's population is Muslim, making it the largest Muslim country in the world in regards to number of adherents. Among the last 15% of the population, about a third of them are Protestant Christian and there are also smaller numbers of Roman Catholics and Hindis.
Islam (the name of the religion, whose followers are called Muslims) is a monotheistic religion, whose holy book is called the Qur'an. The Qur'an is believed to be the word of God spoken through the prophet Muhammad from 609-632 CE (Common Era is preferred over AD (Anno Domini or "year of the Lord") since the Islamic world doesn't believe Jesus was the messiah). Islam believes Muhammad was the last prophet sent to earth by God, the last in a long line of prophets, which includes Moses, Abraham, and Jesus among others.