In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Imaam As-Sadi [may Allaah have mercy upon him] said: “What we have stated (regarding the fact that Islam solves all problems etc) is proven – regarding its truth and correctness – by what has been experienced and clearly perceived through the five senses, just as the (uncorrupted) divine laws, (uncorrupted) natural dispositions and sound minds indicate its reality. That is because the entire religion (of Islam) is righteousness and a means of upright rectification- all of it repels evil and harm, calls to goodness and guidance, and warns against evil and all kinds destructive things”.
Commentary: The state of affairs bears witness to this, and the meaning of this is that many of the problems which people seek to solve based on other than the Qur’aan and the Sunnah have not been solved in a sound manner; but they found a cure (or remedy) after returning to the Qur’aan and Sunnah. This is known in relation to both widespread problems and problems that affect individuals. Many times a person is faced with a problem and he searches – due to lack of understanding – for something to solve it, but through the divine revelation; then he finds that the affair has not increased except in more problems and his calamity has not increase except in more evil, so he reflects and finds that what will stop his problem is found in Islam. For example, the person who faces financial problems may not perceive that his problem did not occur except due to engaging in some forbidden dealings- enters into usury and the likes, and after a period of time it becomes clear to him that his problem only increase in severity, even though the divine guidance puts a stop to problems associated with poverty, riches and illness. Many times people enter into forbidden things when seeking to solve the problem of illness and the affair only increases in severity, and the problem brings other problems. Details will follow from a very beneficial Prophetic narration as to how Islam solves the problem of poverty and illness, and what Islam’s guidance is regarding these problems. Allaah [The Exalted] said:
[ إِنَّ هَـٰذَا ٱلۡقُرۡءَانَ يَہۡدِى لِلَّتِى هِىَ أَقۡوَمُ وَيُبَشِّرُ ٱلۡمُؤۡمِنِينَ ٱلَّذِينَ يَعۡمَلُونَ ٱلصَّـٰلِحَـٰتِ أَنَّ لَهُمۡ أَجۡرً۬ا كَبِيرً۬ا – Verily, this Qur’an guides to that which is most just and right and gives glad tidings to the believers (in the Oneness of Allah and His Messenger, Muhammad , etc.). who work deeds of righteousness, that they shall have a great reward (Paradise)]. [Surah Al-Israa. Verse 9]
And Allaah describes the Qur’aan that is an explanation of everything (see footnote a), but despite this many of Muslims do not return to it due to many reasons and the greatest of them being the existence of much ignorance, little understanding and gatherings of knowledge, and their weak understanding in the religion ordained by Allaah. (1)
Footnote a: “And We have sent down to you the Book (the Qur’an) as an exposition of everything, a guidance, a mercy, and glad tidings for those who have submitted themselves (to Allah as Muslims)”. [Surah An-Nahl. Verse 89]
[Ref 1: Listen to audio here: https://www.al-badr.net/detail/UY7sjBcaQE. from 12mins 34secs to 19mins 41secs. Paraphrased Excerpt]