Assalaamu alaykum. My question relates to having absolutely certainty about the core values/beliefs of Islam, like believing that Allaah is one, that He does not have a son, and so on. My friend says that very few things are absolutely certain in life, including most hadiths and the core values/beliefs of our creed. He said that we are obligated to belief in the authentic hadiths of our Prophet, sallallaahu 'alayhi wa sallam, and the core values/beliefs of our creed because they are very likely to be correct, not because we are absolutely certain that they are authentic and correct. This clearly contradicts what I know, which is that the core beliefs of islam and some hadiths of our Prophet are absolutely authentic. Please, I would be grateful if you could answer my question and not refer me to already answered questions on your site. This question is really causing waswas (devilish whisperings) in my mind.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.

The statement that we are not absolutely certain about the authenticity of the fundamentals of our creed and its principal values is false. Doubting the fundamentals of Islam and the tenets of creed, about which there is no doubt, and doubting the Prophecy of Prophet Muhammad is the most serious thing that could come to one’s heart; this is one of the lures and whispers of Satan and one of the reasons of deviation and destruction.

If a person feels anything of this, then he must hasten to return to Allaah, seek His Help, hold fast to His strong Rope, and supplicate Him in secret and in public; he should do so with humbleness and devotion so that Allaah will repel this from his heart and relieve him of these misconceptions.

A person cannot be a believer unless he firmly and decisively believes in the meaning of the shahaadah (declaration of faith): None has the right to be worshipped but Allaah and Muhammad is the Messenger of Allaah. Allaah says (what means): {The believers are only the ones who have believed in Allaah and His Messenger and then doubt not but strive with their properties and their lives in the cause of Allaah. It is those who are the truthful.} [Quran 49:15]

The Prophet said, “I bear witness that none has the right to be worshipped but Allaah and that I am the Messenger of Allaah; no one meets Allaah while testifying this without having any doubt in it [i.e. in this declaration] except that he enters Paradise.” [Muslim]

The condition for entering Paradise by saying this is to firmly believe it in one's heart without having any doubt about it. If this condition is not met, then there is no entering Paradise.

Similarly, many of the Prophetic ahaadeeth include:

- al- 'ilm adh-dharoori (the necessary knowledge, i.e. the certain knowledge which is to be believed in by everyone because it is based upon tawaatur [i.e. being reported by a group of narrators from a group of narrators, generation after generation and so forth, and they are all trustworthy people and it is absolutely impossible for them to agree on a lie]) such as the mutawaatir ahaadeeth or

- al-'ilm an-nathari (the inductive knowledge, i.e. the certain knowledge that is based upon investigation), such as the ahaadeeth that have been received with acceptance by the entire nation, like most of the texts of the ahaadeeth reported by Al-Bukhari and Muslim.

Shaykh Ibn Taymiyyah said:

“Certain knowledge becomes known sometimes by many people informing about it, and it may become known by only a few people reporting it too, but these people are known for their adherence to their religion and their firm memorization [of the religious texts], and it may become known by indications that strengthen the hadeeth to be authentic; this certainty may happen about some ahaadeeth apart from others.

Also, the hadeeth that the imaams have received with acceptance and have believed in it and acted according to it indicates that the majority of the scholars from among the successors and the Salaf (righteous predecessors) are certain about it; this is in the meaning of the mutawaatir ahaadeeth. But some scholars call it the mashhoor (a hadeeth that is handed down by at least three or more narrators and does not reach the state of Mutawaatir). They classify the ahaadeeth into: mutawaatir, mashhoor and aahaad (the hadeeth which is narrated by a number of narrators less than the Mutawaatir).

Since this is the case, most of the hadeeth texts reported by Al-Bukhari and Muslim are known with certainty and firmness and the scholars of hadeeth received them with acceptance and certainty, and they agreed in a consensus that these ahaadeeth are authentic. Their consensus is infallible. If the jurists agree in a consensus about a fiqh ruling, then their consensus is evidence, even if they relied only on one hadeeth, or an analogy or a generality.

Likewise, if the scholars of hadeeth agree in a consensus about a hadeeth that it is authentic, then this proves certainty, even if one of the scholars may be subject to error but their consensus is infallible.” [End of quote]

Ibn Hajar said in an-Nukhbah, “The first category is the mutawaatir which gives the benefit of certain knowledge if its conditions are met. These conditions are as follows: It is reported by such a large number of narrators that under normal circumstances it would be impossible for them to conspire a lie. Such a number exists throughout the chain of narration, i.e. from the beginning to the end. The reporters must base their report on sense perception, i.e. on something that is heard or seen. That the narration necessitates certain knowledge for the listener.” [End of quote]

He also said: "They - the aahaad reports - may encompass the accepted and the rejected since using them as evidence hinges on investigating the status of the reporters, contrary to the first category (the mutawaatir). Yet they might contain what conveys al-ʿilm an-nathari (the inductive knowledge) with external indicators, according to the preferred opinion, such as when Al-Bukhari and Muslim narrate the hadeeth in their Saheeh, or that the hadeeth is mashhoor (handed down by at least three or more narrators and does not reach the state of Mutawaatir) and conveyed through numerous chains of narration that contain neither a weak narrator nor a concealed flaw (ʻillah), or that it is musalsal (which is the hadeeth whose isnaad [chain of narration] from its beginning to its end is under one formula or situation for the narrators sometimes and for the narration at other times, regardless of whether the narration is about a statement, or an action, or both) and it was reported by imaams who firmly memorized the texts in a way that it is not ghareeb (a hadeeth is termed ghareeb [scarce or strange] when only a single reporter is found relating it at some stage of the isnaad)" [End of quote]

Allaah knows best.