It is the former which ties all Muslims together and is based on the religion of Islam. This includes the Arabic language - all Muslims are expected to learn this, if it is not their native tongue, so that they can read the Qur'an and other Islamic religious texts, such as Hadith. Translations of the Qur'an are not normally used in Islam as it is believed that it is Allah's word (i.e. God's word) and no human being could translate it adequately.

Of course, the two parts of the culture mentioned above cannot be completely separated - each affects the other. The effect of society on religion tends to lead to cults (although there are also other reasons for this). In non-Islamic countries, or where Muslims are a minority, the effect of the religion on Muslim society tends to lead to Muslims living in enclaves and/or standing out from other sections of society.