Why should an apostate be killed according to the Sharia of Islam?

Faith is a relationship between the slave and his Lord, whenever he wants to sever it, his matter is left up to Allah. However, if he declares it publicly and uses it as a pretext to fight Islam, betray it, and distort its image, then, according to the man-made war laws, he must be killed and this is indisputable.

The confusion that led to such an allegation about the punishment prescribed for apostasy stems from the illusion that all religions are equally sound, and considering faith in the Creator and worshiping Him alone and exalting Him above all deficiencies and flaws equal to disbelief in His existence, or the belief that He is embodied in the form of a human or stone, or that He has a child, while Allah is far exalted above that. The reason behind this illusion is the belief in the relativity of creed, i.e., it is possible that all religions are true, which is impossible according to the basic rules of logic. It goes without saying that faith contradicts atheism and disbelief. Hence, the one who adopts the sound creed finds that belief in the relativity of the truth is nothing but heedlessness and logical foolishness. Consequently, it is invalid to deem two contradicting creeds true.

Despite all this, the apostates who rejected the true religion are never subject to the prescribed punishment as long as they do not declare their apostasy, and they know that very well. However, they ask the Muslim community to open the door for them so they can spread their ridicule of Allah and His Messenger without being called to account and urge others to adopt disbelief and disobedience and this, for instance, is what no king accepts or allows in his kingdom. No king would accept that any of his subjects deny his existence or ridicule him or any of his courtiers, nor would he accept that someone would attribute to him what does not befit his status as a king. If this is the case with worldly kings, how about the King of all kings and the Creator and Sovereign of everything?!

Some also think that if the Muslim commits an act of disbelief, he becomes immediately subject to the execution of the prescribed punishment. The truth, however, is that there are excuses that might prevent deeming him a disbeliever in the first place, like ignorance, false interpretation, compulsion, and mistake. This is why the majority of scholars confirmed the fact that an apostate must be asked to repent due to the probability of him being confused about the truth, with the exclusion of the combatant apostate. [156] Ibn Qudāmah in "Al-Mughni".

Muslims used to treat the hypocrites the way they treat normal Muslims, granting them all their rights, despite the fact that the Prophet (may Allah's peace and blessings be upon him) knew them and informed Huzhayfah, his Companion, of their names; however, such hypocrites did not declare their disbelief.