Below is the summary of remarks of Hojat-ol-Islam Reza Berenjkar, an expert in Kalam, about the issue:
Practical theology seeks to control and manage the sufferings that individuals feel. It uses theoretical frameworks and is not after framing theological questions. This approach is similar to that in the medical field as it detects the patient’s pain and prescribes medicine accordingly; medicine here is like practical theology.
Islamic theology has a number of principles including believing in God Almighty, believing in the afterlife, and believing in the temporariness of this world. The purpose of life is to reach perfection and this will not be attained without determination, testing, and suffering. “Every soul has to experience the taste of death. We test you with both hardships and blessings. In the end you will all return to Us.” [21:35]
The worldly good and evil are able to turn against themselves and be detrimental or beneficial to the man. The Quran says: “Fighting is made mandatory for you, but you dislike it. You may not like something which, in fact, is for your good and something that you may love, in fact, may be evil. God knows, but you do not know.” [2:216]
Philosophy of divine punishment
The aim of divine punishments is to wake up the man and return him/her to God. Some of the verses in the Quran name the corruption of the man as the cause of some punishments; “To those who have said, "God is our Lord, " and who have remained steadfast to their belief, the angels will descend saying, "Do not be afraid or grieved. Receive the glad news of the Paradise which was promised to you.” [41:30] Of course, those sufferings that are not punishment have other philosophies as they may happen to assess one’s faith or promote one’s spiritual power.
Answer to those who neither seek worldly suffering nor paradise
Some people may say they neither want suffering in this world nor paradise. First of all, attaining paradise is not hard, but even if there is no paradise, we prefer a life filled with suffering and pleasure to the state of ‘not to be’. All people, even atheists live with suffering but very few of them commit suicide.
We have two paths ahead; one is to try to increase pleasures and decrease suffering and the other is to protest and become disappointed while facing hardships. Now, letting God into this equation will promise a good life in the next world.