“And indeed We have put forth for men, in this Qur'ân every kind of similitude in order that they may remember.

An Arabic Qur'ân, without any crookedness (therein) in order that they may avoid all evil which Allâh has ordered them to avoid, fear Him and keep their duty to Him”

[al-Zumar 39:27-28]

The Arabic Language is the key that opens the door when it comes to Islamic Knowledge, Allah (سبحانه وتعالى‎) chose it over all other languages to be the last revelation to humanity and he chose the Arabs to convey it, in it's Arabic form, to the rest of the world. It is essential to learn Arabic if one wants to grasp some sort of understanding of the Quran, translation of the Quran implies a human factor and takes away from the eloquence, perfection and essence of the Quran. Learning Arabic and teaching it to our children should be at the forefront of our priorities. It is the symbol of Islam and the language of the muslims, it has nothing to do with nationalism, infact the greatest scholars of the Arabic language were non-arabs, such as Sibawayh, the grandfather of Arabic grammar, who was in fact a Persian.

Shaykh al-Islam Ibn Taymiyyah (رحمه الله) said: 

The Arabic language is the symbol of Islam and its people. 

( Iqtida’ al-Siraat al-Mustaqeem, 1/519)

And he also said in another place,

...this is because the (language) that Allah choose is Arabic. He revealed His glorious book in this language and He made it the tongue of His final and last prophet, Muhammad (صلى الله عليه وسلم). Therefore, we say: it is befitting for everyone that has the ability to learn this language to do so, this is because it should be the most desired language to learn. At the same time, it is not forbidden for people to speak with other than the Arabic language.

( Iqtida’ al-Siraat al-Mustaqeem, 1/521)

Insha'Allah on this website you will find adequate resources to learn Arabic.