Verse 19 of Surat Muhammad means:
[O Muhammad, be firm in knowing that no one is God except Allah.]
In the hadith related by al-Bayhaqiyy, the Messenger of Allah sallallahu ^alayhi wasallam said what means: <<Seeking the knowledge of the Religion is obligatory on every Muslim (whether male of female).>>

The wording of this hadith the term <<every>> (kull) from which the scholars clearly understood <<the Personal Obligatory Knowledge of the Religion,>> and not all kinds of knowledge. Had every kind of knowledge been obligatory on every male and every female, it would have been a hardship beyond one's ability, and Allah does not order anyone with what one cannot bear.
Imam Abul-Hasan al-Ash^ariyy said: <<The first obligation on the slave is to learn about Allah, His Messenger, and His Religion.>>

The knowledge of the Religion entails many facets and many subjects among which are the knowledge of Tawhid and the knowledge of the rules of the Religion. The knowledge of Tawhid entails knowing about Allah and His Messenger, and it is the best of all the knowledge in Islam. The scholars repeatedly emphasized the clear evidence from the Qur'an, Hadith, and scholarly consensus proving the knowledge of Tawhid is ranked the highest among all knowledge. This is so, because it has to do with knowing about Allah and about His Messenger. This entails knowing what befits Allah and what is impossible to be among His attributes, and what befits the messengers and what is impossible to be among their attributes.
Imam Abu Hanifah may Allah raise his rank said: << Tawhid is the <<Great knowledge (al-Fiqhul-Akbar).>> Imam ash-Shafi^iyy may Allah have mercy on him said: <<I mastered the knowledge of Tawhid before mastering the knowledge of the rules of the Religion.>>

This knowledge of Tawhid is of two categories:
1. The first category is that which is obligatory on every accountable person (The accountable person is the one who is pubescent, sane, and has heard the Testification of Faith in a language one understands.). The accountable person is obligated to know this knowledge; hence, this category is classified among the Personal Obligatory Knowledge. Examples of this knowledge include the belief in Allah and the belief in His angels, His books, His Messengers, the Day of Judgment, destiny, and the like.

2. The second category of this knowledge of Tawhid is that which is obligatory for some Muslims to master, but not all Muslims. This obligation is classified as a communal obligation (Fard Kifayah), since if some of the Muslims have that knowledge, obtaining it is no longer an obligation on the rest of the community. Examples of this category is for one to learn the proofs of the tenets of belief from the Qur'an, Hadith, and intellect to enable one to refute the claims of the enemies of Islam, like the communists and the innovators of misguidance. Also, among the communal obligations is that some Muslims must acquire the sciences Muslims need, such as medicine, engineering, agriculture, and the like. Hence, if enough Muslims learn these sciences such that they satisfy the need of the community, it is no longer obligatory on the others.

The first category of the knowledge of Tawhid, the personal obligation, has two subdivisions. The first subdivision entails knowing correctly about Allah and His Messenger and believing in it beyond doubt. If one does not know and believe this, one will not be a Muslim, and one who dies as such will not escape the everlasting tortures of Hellfire. However, having satisfied this and having uttered the Testification of Faith at least once in one's lifetime, but failing to obtain other essentials of belief and to fulfill other obligations, such as fasting and praying and the like, one becomes a sinful Muslim, provided one does not deny the obligation of fasting, praying, and the like (Denying these commonly known obligations renders the person non-Muslim because it entails belying Allah ta^ala and his beloved Messenger peace be upon him).
The second subdivision entails learning the thirteen attributes of the Self of Allah which are obligatory on every accountable person to know, and learning the attributes of the prophets and believing in what they taught regarding the angels of Allah, the Books of Allah, the Messenger of Allah, the Day of Judgment, destiny, whether good or evil - Paradise, and the like.
As to the rules of the Religion (known as Ahkam or Islamic Jurisprudence), part of this knowledge is a personal obligation. The Muslim who is accountable is obligated to learn the matters of Purification (Taharah), the rules of prayers, the rules of fasting, and the rules of other obligations that apply to him, including Zakah, Pilgrimage, dealings, sins of the body, and the like.

Learning the Personal Obligatory Knowledge of the Religion protects one from evil and leads one to piety:
Learning the Obligatory Knowledge of the Religion makes one able to discriminate between what is lawful (halal) and what is unlawful (haram), what is valid and what is invalid, what is acceptable and what is rejected, in addition to what is classified under the Religion as good or bad. The scholars of Islam have spoken explicity about these criteria. In the chapter entitled <<Knowledge Before Saying or Committing Action,>> Imam al-Bukhariyy may Allah raise his rank stated: <<If one acquires the Obligatory knowledge of the Religion, one acquires the ability to differentiate between what is lawful and what is unlawful, what is acceptable and what is not acceptable, and what is good and what is evil.>>
Verse 6 of Surat at-Tahrim means: [O believers, protect yourselves and your families from Hellfire which is fueled by people and stones.] Imam^Ata' Ibn Abi Rabah who was among the followers of the Companions, interpreted the above mentioned verse of the Qur'an. He said: <<One protects himself and his family from the tortures of Hellfire by learning how to pray, fast, sell, buy, marry, and divorce.>>
Verse 56 of Surat adh-Dhariyat means: [I created the jinn and humans to order them with worship.] We have been created to be ordered to worship Allah. Worshipping Allah requires knowledge. For one to have a valid worship, first one must have the correct belief in Allah. Imam al-Ghazaliyy said: <<The worship is only valid after knowing correctly about Allah.>> Hence, if one learns that knowledge of the Religion, one will know how to perform the worship; one will know what is lawful and what is unlawful and what is acceptable and what is not. By implementing this knowledge accordingly, one earns the reward on the Day of Judgment. This knowledge is not limited to particular groups of people. All people are in need of this knowledge to carry out their tasks in compliance with the rules of Allah. This includes parents, teachers, carpenters, doctors, engineers, and others.

The cure for the agonies many of our communities face depends on the extent of our obedience to Allah in applying the rules of the Religion. The one who learns the Religion and implements it satisfying the methodologies and criteria of seeking knowledge is pious and sincere. If such a person wants to marry, he conducts his marrige in a valid manner. He observes what is lawful and unlawful in the marital relationship; he fulfills his obligations, and he fears Allah. Since he knows how to have a valid marriage contract, his children will not be a result of adultery. He eats and drinks what is lawful, dresses in what is lawful, and lives in a lawful place, because he differentiates between what is lawful and what is unlawful. He neither takes someone else's place by force nor cheats others, because he observes the rights of others. If he goes out to buy things, he does so in a lawful manner, because he learned how to transact business according to the rules of the Religion. He implements the great manners the Prophet sallallahu ^alayhi wasallam taught. This person performs his Prayer in a valid way, because he knows what makes the Prayer acceptable to Allah. Likewise, his Fasting, Dry Purification (Tayammum), Pilgrimage (Hajj), Purification, and other aspects will be performed in a valid manner. He does all of that with sincerity to Allah, because he knows this is a condition for earning the reward, the blessings, and the benefits in this life and in the Hereafter.
Once the members of the community attain these qualities, the relationships that govern them will improve, and the society at large will improve. The wealthy person who is sincere and knowledgeable will spend in the path of Allah out of generosity and love, and seeking the reward from Allah. Also, the one who is poor, like other pious people who are poor, will be patient and have complete reliance on Allah. They would implement the hadith of the Prophet peace be upon him: <<If you rely on Allah perfectly, then Allah will sustain you and provide for you as He provides for the birds. The birds fly away from their nests in the morning hungry, yet they return with full stomach.>> Allah will provide for the one who is poor and sincere, and has the proper reliance on Allah, just as He provides for the birds.

Examples of success in this life are to have a valid marriage, buy and sell lawfully, be knowledgeable and implement the knowledge, and perform the Prayers, Fasting, and Pilgrimage in a valid manner. The one who is knowledgeable will be led by his knowledge to piety and sincerity. The one who is pious will fall under the Qusdsiyy Hadith of the Prophet sallallahu ^alayhi wasallam:
<< Allah said: I prepared for My pious slaves in Paradise that which no eye has seen, no ear has heard, and that which has never occurred to the heart of a human being before.>>
The ultimate success is to be successful in the Hereafter. The person who acquires the knowledge as it is prescribed in Islam enters the gateway to success in this life and in the Hereafter. So be eager to acquire that knowledge. Be eager to be around the scholars. Be eager to associate with the scholars, for the Messenger of Allah said what means: <<The scholars on earth are like the stars in the heavens with which one is guided through the darkness of land and sea.>>
At-Tabaraniyy related the saying of the Prophet sallallahu ^alayhi wasallam, in highlighting the importance of the scholars: <<The death of an entire tribe is easier than the death of one scholar.>>
Be warned of those ignorant people the Prophet peace be upon him spoke about in his hadith related by at-Tirmidhiyy:
<< Allah does not take away the knowledge by ordering it to be pulled out of the hearts of the people. Instead, Allah takes the knowledge away by making the scholars die. When no scholar remains, people take for themselves ignorant leaders whom they ask for religious answers. These leaders will answer them with ignorance, thus straying and leading them astray.>>

We humbly ask Allah to grant us the knowledge that is beneficial to us, to benefit us with this knowledge and to increase our knowledge. Ameen.

And Allah knows best.