Why did Islam permit killing under certain conditions, knowing that the soul belongs to Allah alone, and is what is mentioned in the Quran about killing incorrect?

To answer the question "Isn't the soul the sole property of Allah?", indeed, it is the sole property of Allah. Therefore, it is not killed except with His permission and by His law, which He revealed in His Book or through the tongue of His Messenger. Killing without His law is oppression and aggression, whereas killing by His command is truth and justice, and there is no justification for objecting to it, because He, glory be to Him, is the Owner of souls and the Legislator of their killing in specific instances.

For a fair judgment of Islamic rulings, one must understand the cases in which Islam permits or commands killing, and then know its measures to prevent unlawful killing. These include: the prohibition of suicide, the prohibition of everything that harms the self, the prohibition of abortion, the prohibition of killing a soul unjustly (including those with whom covenants are made and dhimmis), averting punishments due to doubts, restricting the death penalty to grave crimes such as apostasy, adultery for a married person, and unlawful killing, severe deterrence against killing, and confining the execution of the death penalty to rulers and the legitimate judiciary, not to individuals.

Furthermore, retaliation (qisas) aims to preserve life, for it deters murderers and protects society. This is affirmed in the Quran, where Allah Almighty says: "And there is for you in legal retribution [saving of] life, O you [people] of understanding."

Finally, it is observed that the number of those killed during the time of the Prophet, peace and blessings be upon him, did not exceed a thousand, whereas thousands of souls are killed annually under Western laws. This objection is strange coming from a Christian who believes in the Bible, which legitimizes killing in huge numbers, including the killing of entire nations of males, females, and children, which far exceeds what is stated in Islamic Sharia (definition).