Praise be to Allah, and peace and blessings be upon the Messenger of Allah. To proceed:
The religion of Islam is perfect and contains no deficiency whatsoever. Its perfection is among the effects of the perfection of Allah, Exalted be He, because it is the religion that Allah legislated, and He is perfect in His knowledge, wisdom, mercy, justice, and power.
Allah has informed us of the perfection of this religion in His saying:
“Today I have perfected for you your religion, completed My favor upon you, and have chosen Islam for you as your religion.”
[Al-Ma’idah 5:3]
And He, Glorified be He, says:
“The Word of your Lord has been perfected in truth and justice. None can change His Words, and He is the All-Hearing, the All-Knowing.”
[Al-An‘am 6:115]
Ibn Kathir, may Allah have mercy on him, explained that the perfection of Allah’s Word means that it is truthful in its reports and just in its rulings. Whatever Allah informs us of is true without doubt; whatever He commands is just; and whatever He prohibits, He prohibits because of the harm and corruption it contains.
Islam is therefore perfect in its beliefs, reports, laws, and rulings. It contains no deficiency that anyone needs to correct or complete.
The statement that the religion is perfect because it comes from Allah, who is perfect in His attributes, is correct. Allah is perfect in knowledge, wisdom, mercy, justice, and power. Therefore, His Shariah contains that which brings about the interests and welfare of His servants and guides them to what is beneficial for them.
Allah says:
“Say: It was sent down by the One who knows the secret within the heavens and the earth. Indeed, He is Ever-Forgiving, Most Merciful.”
[Al-Furqan 25:6]
And He says:
“And indeed, you receive the Qur’an from One who is All-Wise, All-Knowing.”
[Al-Naml 27:6]
The Qur’an contains reports concerning the past and the future, and such reports cannot be perfect unless they are truthful and correspond to reality. It was revealed by Allah, whose knowledge encompasses both what is hidden and what is apparent.
Likewise, the rulings of the Shariah cannot reach the highest degree of perfection unless they come from a Legislator who is perfect in knowledge and wisdom. He legislates only what contains benefit, prohibits only what contains harm, and His rulings do not contradict one another.
Allah says:
“Do they not then reflect upon the Qur’an? Had it been from other than Allah, they would surely have found in it much contradiction.”
[Al-Nisa’ 4:82]
And He says:
“Indeed, it is a mighty Book. Falsehood cannot approach it from before it or from behind it. It is a revelation from One who is All-Wise, Praiseworthy.”
[Fussilat 41:41–42]
The perfection of Islam is not limited to beliefs and rulings. It also includes what Allah has promised to those who obey Him and what He has threatened those who disobey Him with.
The promise of bliss is appropriate for righteous deeds, while the warning of punishment is founded upon justice. Allah is perfect in mercy and justice, just as He is perfect in His power to carry out what He has promised and warned of.
Allah says:
“Indeed, your Lord is the Almighty, the Most Merciful. And indeed, this is a revelation from the Lord of the worlds.”
[Al-Shu‘ara’ 26:191–192]
And He says:
“The revelation of the Book is from Allah, the Almighty, the All-Knowing; the Forgiver of sin, the Accepter of repentance, severe in punishment, the Possessor of abundance. There is no deity worthy of worship except Him; to Him is the final return.”
[Ghafir 40:2–3]
Allah also says:
“It is the promise of Allah. Allah does not fail in His promise.”
[Al-Zumar 39:20]
And He says:
“Allah does not intend injustice for the worlds.”
[Aal ‘Imran 3:108]
All these meanings show that the perfection of the religion is connected to the perfection of the One who legislated it. Allah is perfect in His knowledge and wisdom, perfect in His mercy and justice, and perfect in His might, power, and sovereignty. Therefore, His Shariah came in the utmost perfection.
Yes, it is correct to say that the perfection of the religion of Islam is among the effects of the perfection of Allah in His attributes. Allah, Glorified be He, is perfect in His knowledge, wisdom, mercy, justice, and power, and therefore He legislated for His servants a perfect religion containing no deficiency.
Islam is perfect in its beliefs, reports, laws, rulings, promises, and warnings. This is among the effects of the perfection of Allah’s knowledge, wisdom, mercy, and justice.
And Allah knows best.