What is the difference between Muslims saying “we don’t describe the ‘hows’ of Allah’s attributes” and Christians saying the same about the Trinity?
In Islam, it is not permissible to describe the “hows” of Allah’s Attributes because of Allah’s statement:
“Allah knows what is [presently] before them and what will be after them, and they will never encompass anything of His Knowledge.” 
The human mind cannot comprehend how Allah’s attributes operate. Taking the names and attributes mentioned in the Qur’an and Sunnah at face value, without any comparison, alteration, negation or takyeef (asking how) is the method of the companions of the Prophet (ﷺ), their followers and those who followed their followers.
A man came to Imam Malik bin Anas and asked him, “O Malik! The Qur’an says that Ar-Rahman ascended the Throne; how did He do that?” Malik was extremely disturbed by this question, and replied:
“The Istiwaa’ (ascendance) is known [in meaning]; but ‘how’ it took place is not known [to people]. Believing in its occurrence is compulsory; and questioning its mode of occurrence is a bid’ah (a rejected innovation in the Faith). And I believe indeed that you are committing a bid’ah [by asking this question].” The man was then banished from his class.
This example demonstrates the gravity of questioning the “hows” of Allah’s attributes. It also shows that there is support for this argument (not asking about the “hows” of Allah) in the authentic texts of the Sunnah.
Now, let us examine how the Christians not asking about the “hows” of the Trinity is different from the Muslims not asking about the “hows” of Allah. First of all, the Christians’ belief in the Trinity (that God is one in three) clearly contradicts the obvious meanings of their texts. The Bible emphatically states there is only One God:
- “Hear, O Israel: The LORD our God is one LORD.”
- “Know that the LORD is God; besides him there is no other.” 
- “I am the first and I am the last; apart from me there is no God.” 
- “How can you believe if you accept praise from one another, yet make no effort to obtain the praise that comes from the only God?” 
The second point is that the Christians do not have any authentic evidence to support their claims. The Trinity that the later Christians have fabricated has no evidence in reason and fitrah (natural disposition), and there is nothing to support it in the divinely-revealed books which Allah sent down. Rather, the Trinitarian view of Christianity came into being many years after the disappearance of ‘Isa (‘alayhi salam). Undoubtedly, it was not professed by ‘Isa nor by the other prophets. As a matter of fact, the true followers of ‘Isa (‘alayhi salam) continued to affirm the Oneness of God until about 90 CE. This belief in the Unity of God was manifested in the Shepherd of Hermas, which was written during this period and regarded as a book of revelation by the earlier Christians. More specifically, the first of these commandments states: “First of all, believe that God is One and that He created all things and organized them out of what did not exist made all things to be, and He contains all things but alone is Himself uncontained.” 
Prior to 200 CE, the term “Trinity” (which is now the nucleus of the Christian tenets) was not at all known to the Pauline (Roman Catholic) Church. The early Unitarian leaders were courageous enough to expose their views to refute the Trinitarian dogmas, in spite of the persecution campaign against them. Their real champion, however, was Arius who in 318 CE popularly opposed the Pauline view that ‘Isa (‘alayhi salam) was in reality the “Son of God” and “con-substantial and coeternal with the father”. One of the arguments propagated by Arius was: “If Jesus was in reality the ‘Son of God’, then it followed that the father must have existed before him (the son). Therefore, there must have been a time when the son (Jesus) did not exist. Therefore, it followed that the son was a creature composed of an essence or being which had not always existed. Since God is in essence eternal and Ever-existent, Jesus could not be of the same essence as God.” 
In 321 CE, Arius popularly confronted Bishop Alexander the forerunner of the Pauline Church. In 325 CE, Emperor Constantine convened the First General Council at Nicaea. This Council was attended by 318 bishops from Spain to Persia.
In 380 CE, Emperor Theodosius of Rome made the orthodox faith (the Trinitarian-based Catholic faith) obligatory for all his subjects, hence the state religion since then. By 383 CE, Theodosius threatened to punish all who would not believe in the doctrine of Trinity. Thus, the concept of the Trinity is foreign to the teachings of Christianity. It was a man-made innovation. Furthermore, the word “Trinity” is not found in the Bible, and no single verse provides a summary of the Trinitarian doctrine. Actually, it must be remembered that the Old Testament was written before the revelation of the doctrine of the Trinity was clearly given, and in the New Testament after it. How then can the absence of such an allegedly profound doctrine not be found in sacred texts? Surely these are ample proofs illustrating that there is no authentic text to support the concept of the ‘Trinity’ in Christianity.
Finally, Allah has refuted the concept of the Trinity in the Qur’an:
“They have certainly disbelieved who say, "Allah is the third of three." And there is no god except one God. And if they do not desist from what they are saying, there will surely afflict the disbelievers among them a painful punishment.” 
And so it is quite clear, that questioning about the “hows” of the Trinity cannot be likened to questioning the “hows” of Allah’s attributes. The Trinity is itself an innovation, which makes it questionable; whereas, Allah’s attributes are confirmed by Himself, which we are supposed to believe without questioning, since the human mind can never comprehend the taykeef (asking ‘how’) of Allah’s attributes. Something which is confirmed by the Creator Himself and mentioned in a way that befits Him needs no further questioning. Hence, the difference between the two “hows” is that the Muslims’ reason is based on authentic texts, which do not contradict the Qur’an (our text); whereas it is the opposite for the Christians.
And Allah knows best.
 Surah at-Taha, 20:110
 Al-Bayhaqee in al-Asmaa was-Sifaat, p. 408; Ad-Darimee in ar-Radd ‘ala al-Jahmiyyah, p. 141-2; and Al-Lalka’ee in Sharh Usul ‘Aqeedah Ahlis-Sunnah, p. 664
 Deuteronomy 6:4, Mark 12:29
 Deuteronomy, 4:35
 Isaiah, 44:6
 John, 5:44
 E. J. Goodspeed, The Apostolic Fathers, 1950; quoted by Muhammad Ata ur-Rahman, op. cit., 1984, p.46
 Muhammad Ata ur-Rahim, Jesus: Prophet of Islam, p.88
 Surah Al-Ma’idah, 5:73< Back to Questions