al-Salāmu ‘alaykum wa rahmatullāh,
The Arabic language no doubt has a special place in Islam because it is the language of the Qur'an, and the importance of Arabic to each Muslim is proportional to their relationship with the Qur'an and how deeply they seek to understand it.
Thus, the Muslim must be vigilant in protecting and preserving the Arabic Language, and this vigilance is related to his vigilance and protectiveness of the religion itself, for one complements the other and strengthens the other, like a building and its foundations.
An argument in favour of Arabic states : Language is a means by which history is manifested and expressed, and history narrates the character of a people and their nation, and a nation may be said to be crafted by its language because it is one of its inherant, natural needs that cannot be replaced by another. And the Qur'an in this regard represents a linguistic nationality that gathers together all the believers in Tawheed, through the Arabic language.
 Adapted from the book al-Bu'd al-Deeni li-al-Lughah al-'Arabiyyah wa atharuhaa fi al-Tadaamun al-'Arabi wa al-Islaami by Dr. Muhammad Sikhani, Dar Qutaybah: Beirut, pg 66-68