Believing in qadr (destiny) can make you spiritually and emotionally happy and here is how and why
We test you with Evil and with good as a trial (Surah Anbiya, verse 35)
From the five pillars of Emaan, Qadar is one of them and many people understand Qadar as destiny. So believing in Qada and Qadar is a part of faith. In Islam, "predestination" is the usual English language rendering of a belief that Muslims call al-qaḍāʾ wa al-qadr. The phrase means "the divine decree and the predestination." Qada means, Allah has decided and written down everything that is going to happen, thousands of years before creating the world. This includes, even the gender of each child that is born, every leaf that falls, the landing place of every drop of rain is recorded before Allah created the universe. Thus deciding of the entire creation’s acts is called Qada and from this root word we have the word ‘Qadi’ which means one who delivers a decision and the court where such decisions are given are known as ‘ Darul Qada.’ Therefore we believe that Allah has decided about each and everything that exists according to His supreme wisdom.
Allah has decided each thing as per his complete knowledge. He knows best who should he give wealth and who should be deprived of it. He has created everything in a right proportion and its distribution is also decided. This is known as Qadr. There the combined meaning of Qada and Qadr is called taqdeeer. The importance of believing in Taqdeer is found in many verses of Qur’an and Hadith e Jibrael. Allah sent Jibrael to teach the Muslims about Emaan and Taqdeer was a part of that lesson. The way we believe in the existence of Allah, His Messengers, His books, His Angels, The Day of Judgement, similarly, we are supposed to believe in Taqdeer too.
It is compulsory to believe in Qada and Qadr
The Messenger of Allah (peace be upon him) said, “Allah will not accept the charity of a person, even if it as huge as gold equivalent to the size of mount Uhud, until the person believes in Taqdeer.” This shows that believing in Taqdeer is a condition for the acceptance of good deeds and this belief should be without any doubt or confusion. It is Allah’s decision to give as much as wealth, life and health. Illness, wealth, good health, long and short life are all given as a part of test for every human. “We test you with Evil and with good as a trial.” These tests are to check people’s behaviour and character as well as their faith.
Human beings undergo different types of difficulties and each one is destined to face such trials in life , “And We will surely test you with something of fear and hunger and a loss of wealth and lives and fruits, but give good tidings to the patient, Who, when disaster strikes them, say, "Indeed we belong to Allah , and indeed to Him we will return."Those are the ones upon whom are blessings from their Lord and mercy. And it is those who are the [rightly] guided.” (Surah al Baqarah, verse 155-157)
Allah tests will not only through difficulties but also through luxury and easiness in life as well. If illness, poverty and loss in life are tests to check a person’s patience, then a sound health, richness and profit are also tests to check if the person is grateful or arrogant. The entire good deeds revolve around Sabr and Shukr, i.e. Patience and Gratefulness.