The amount of knowledge a Muslim is required to learn

Question: Is there a specific amount of knowledge that a Muslim should learn in order to understand his religion?

Answer: Yes. It is obligatory for him to learn what is obligatory upon him and what is forbidden for him, while the rest is a recommended practice (sunnah). It is obligatory for him to learn what he cannot afford to be ignorant of; that is, what Allah has made obligatory upon him and what Allah has forbidden for him, so that he worships his Lord with understanding. For Allah says: [Surat al-Dhariyat: 56].
And this worship, for which they were created, must be known by them so that they can perform it. There is no path to knowing it except through Allah, then through beneficial knowledge: by looking into the Book of Allah and the Sunnah of His Messenger (peace and blessings be upon him), and by asking the people of knowledge, as the Exalted said: [Surat al-Nahl: 43]. So let him know; it is obligatory for every Muslim and every Muslim woman to learn what they cannot afford to be ignorant of, and to gain understanding in the religion, so that they know what Allah has made obligatory upon them and what He has forbidden for them, and so that they worship Allah with understanding. For he is created for worship and commanded to do it, so he must learn this worship for which he was created. This is done by reviewing the great Qur'an and the pure Sunnah, and by asking the people of knowledge about whatever is difficult for him.