What! When a single disaster smites you, although ye smote (your enemies) with one twice as great, do ye say?- “Whence is this?” Say (to them): “It is from yourselves: For Allah hath power over all things.”
As mentioned above, some people wrongly believed that a messenger of Allah and his companions are immune from all hardships and difficulties. Also, they believed that when he undertakes any venture, angels would accompany him to help and support him and if he and his companions have to fight, they would always be victorious. Those who had such a notion about the messengers and prophets of Allah, were naturally greatly shaken in their belief by the setback suffered by the Muslims at Uḥud. If Islam were indeed the true religion and Muḥammad, peace be upon him, was the messenger of Allah, why then did he suffer a defeat? The hypocrites tried to exploit this psychological condition of the weaker elements. They presented this defeat as an argument to denigrate the Prophet and his status in the community. The Qur’ān has tackled this misunderstanding at some length in this and the following verses, while explaining the wisdom behind the trials and tribulations that the believers inevitably have to go through.
Firstly, they are told that it is not they alone who have suffered such a setback that should thus plunge them in such suspicion and despair. Their enemies too had suffered a two-fold loss at their hands. In the battle of Badr, they had killed seventy leaders of the enemy while taking another seventy as prisoners. Even in the battle of Uḥud, the Muslims were dominant and some of the enemy were killed and others wounded by them. However, due to their own mistake, they had later suffered defeat. Allah has full control over victory and defeat, but His power is always subject to His wisdom.
Secondly, it is stressed that the Muslims were themselves responsible for their defeat as has been explained above in verse 152: “Allah did indeed fulfil His promise to you when you with His permission were about to annihilate your enemy, until you flinched and fell to disputing about the order, and disobeyed the Prophet after Allah brought you in sight of what you covet. Among you were some who were infatuated with worldly pleasures and others who desired the hereafter. So Allah did divert you from your foes in order to test you but He forgave you, for Allah is full of grace to those who believe.”
Islahi, Amin Ahsan. Pondering Over The Qur’an: Surah Ali Imran (pp. 298-299). Islamic Book Trust. Kindle Edition.