Arabic
Islam
Muslim people went there
Russian is an easy language to learn for some people. For others it is an incredibly frustrating language to learn.
only speak the language you want to learn and hang around people that speak that language.
Yes, of course. Non-Muslims can learn Arabic language and even the Arabic from the Quran without having to convert to Islam.
The English language has adopted words from many other languages- as a result, the vocabulary and rules of grammar are extremely complex (is it you and I, you and me, me and you, I and you, etc) English is one of the harder languages to learn as a second language.
Most of Indonesian learn Indonesian language as second language aside of their local regional language.
Most Brazilians, like most other people, don't go anywhere to learn their native language. They learn it at home as infants and young children.
they think sense they know how to talk in one language then why learn another
Many people do agree it is better for a child to learn another language.
that is english.
People are trying to promote sign language these days. As such, there are plenty of online resources you can use. In fact, a lot of people learn the whole language online!