There is a Divine Wisdom in everything. The greatness and vastness of Allah’s Infinite Mercy and Wisdom stand far above our weak human perception. Whatever the degree of our intelligence is, we will never realize the Divine Wisdom and the aspects of Allah’s Mercy in this universe. This Divine Wisdom is limitless and magnificent and we have but to say: “Glory be to You our Lord! You are the Merciful and the Compassionate.”
Indeed, there is a Divine Wisdom behind the creation of harmful animals, the whole of which is known to none but Allah. Part of this Divine Wisdom is to test people’s faith when they are the victims of harmful animals. We must also keep in mind that what is harmful to us is of great benefit to the animal, allowing it to defend itself or catch its food. Additionally, beneficial drugs may be derived from animal poisons. This is part of the Divine Wisdom behind the creation of harmful animals.
Sheikh M. S. Al-Munajjid, states the following: “The general approach is that the Muslim believes that Allah is All-Wise and All-Knowing, and He does not create anything in vain; all of His actions are based on wisdom. If the wisdom behind any of His actions is hidden from the believer, then he should still adhere to this principle, and not think of his Lord in bad terms.

The specific approach is that the wisdom behind the creation of these things is to manifest the perfect nature of Allah’s creation and control of all things. Even though the created things are so many, He provides for them all. He also tests people by means of these harmful creatures, rewards those who are afflicted by them and makes manifest the bravery of those who kill them. By creating them, He tests people’s faith and certainty: the believer accepts the matter and submits, while the doubter says, “What is the point of Allah creating this?!” He also demonstrates the weakness and incapability of man, whereby he suffers pain and sickness because of a creature that is far smaller than he is.
One of the scholars was asked about the wisdom behind the creation of flies. He said, so that Allah may humiliate the noses of the tyrants with them. Because of the existence of harmful creatures, it becomes apparent how great is the blessing in the creation of beneficial things, as it is said that contrast with the opposite demonstrates the nature of things. The study of medicine has demonstrated that many beneficial drugs are derived from the venom of snakes and the like. Glory be to the One Who has created benefits in things that to all outward appearances are harmful.
Moreover, many of these dangerous animals are food for other creatures that are beneficial, and this forms the ecological cycle in the environments where Allah has created them.
Having clarified the above, I would like to stress that a Muslim has to believe that everything that Allah does is good, and that there is no pure evil in what He Almighty creates. In everything that He creates there has to be some aspect of good, even if it is hidden from us, as is the case with the creation of Satan, who is the head of evil. But there is wisdom and a purpose behind his creation, for Allah tests His creatures with Satan, to distinguish the obedient from the disobedient, those who strive from those who are negligent, the people of Paradise from the people of Hell.
Finally, I implore Allah to bless us with strength of faith and understanding of our religion.”