Is faith merely knowledge, or does it necessitate belief?

The Shaykh : However, there is a subtle point here that few of the commentators on the hadith have pointed out, let alone others. We must be alert to it because it is connected to an important topic related to tawhid (the oneness of Allah) in Islam. This is what is indicated by his statement (peace be upon him) in the answer to the question, where he first said: That is, faith in Allah is the best of deeds. So, is faith in Allah a deed? Here is the subtle point. It is known that faith consists of belief with the heart, and after this belief comes the action of the pillars. The action of the pillars is action with the limbs, but is the faith, whose abode is the heart and mind, itself a deed or not? This is what I want to draw attention to, based on what we have derived from the research of Shaykh al-Islam Ibn Taymiyyah (may Allah have mercy on him), which settles in the heart: it is a deed, because faith is not merely knowledge, as some writers imagine, and they even describe faith as knowledge. This is an incomplete and incorrect expression, because faith includes knowledge, or knowledge must be present with it, but knowledge is not faith. Faith is knowledge plus firm belief in the heart. This belief, which is in addition to knowledge, is the faith that saves with Allah (Blessed and Exalted is He) on the Day of Resurrection.
As for mere knowledge, it contains no action of the heart whatsoever, and knowledge of the truth is equal among believers and disbelievers. (Please hold your questions for later, because we now have three questions that we will answer.) Knowledge is shared by Muslim believers and disbelievers, and the believer is distinguished from the disbeliever by faith in what he has known. You must remember this precise meaning well: faith is something greater than knowledge. Knowledge is mentioned by Allah (Mighty and Majestic) in the Noble Qur'an in more than one place, sometimes by its word and sometimes by its meaning. For example, He describes the People of the Book, and especially the Jews among them, by saying (the Exalted): They know that Muhammad (peace and blessings be upon him) is truthful in his claim that he is the one sent by Allah (Blessed and Exalted is He) to all creation, jinn and humans, but they deny it. The Jews know this truth but they deny it. Our Lord (Mighty and Majestic) also pointed to this denial regarding other groups of polytheist disbelievers, saying (Mighty and Majestic): So, does this certainty, which is knowledge, benefit its possessor? The answer is: No, unless it is accompanied by faith, which is firm belief accompanied by submission and surrender to Allah (Mighty and Majestic). This faith, then, is a heart action; it is not mere knowledge, nor mere information that a person receives and finds himself compelled to believe, without interacting with it or tasting it in his heart, and consequently in his limbs, with this information that he believed in and had faith in. Here is the subtle point when the Messenger (may Allah's prayers and peace be upon him) makes faith the best of deeds. Faith, explicitly in this hadith and in many, many hadiths in "al-Sahihayn" and others, How is it, when faith is a matter of the heart? So we must know that this faith, whose abode is the heart, is a heart action, a movement of the heart that the believer feels. Therefore, just as a person's actions with his limbs increase and decrease, so too does this faith in the heart increase and decrease completely, because it is not mere knowledge that does not accept increase, but rather knowledge accompanied by submission and firm faith. This faith, accompanied by submission and humility, is what caused the difference, unfortunately, among Muslims in the past: does it increase and decrease or not? But there is no harm in the fact that the majority of Muslim scholars have explicitly stated what the many verses from the Book and Prophetic hadiths indicate, including this hadith we are currently discussing, that faith increases and decreases. Because faith in the heart is the action of the heart, and this action increases and decreases just as the action of the heart does in the material aspect. Just as this heart strengthens and weakens in the material aspect, which is witnessed by all people, their healthy and their sick, so too is the faith settled in this heart capable of increase and decrease. It was very fitting that the Prophet (peace and blessings be upon him) pointed to this reality, which is that this faith, whose abode is the heart, is like the heart itself in that it is a morsel that increases and decreases. He pointed to that in the authentic hadith, which is his statement (may Allah's prayers and peace be upon him): At that time, the Messenger of Allah (peace and blessings be upon him) says in this authentic hadith: It does not mean only material soundness, but it has directly exceeded it to indicate spiritual soundness, the spiritual health as they express it today, so he said: So this heart, as we said earlier, sometimes overflows with strength, sometimes with weakness, and sometimes is in between, so too does the faith settled in this morsel increase and decrease. Let no one among the Muslims go to the extent of saying that faith does not increase and decrease, for this is a statement that contradicts, in a clear contradiction, dozens of texts from the Book and the Sunnah that explicitly state the increase of faith. With that statement, one also contradicts this subtle point we are in the process of explaining, which is that faith is a deed, and it is known that a deed accepts increase and decrease, strength and weakness. The subtle point, or the fruit that we should harvest from this knowledge, from the Messenger's (may Allah's prayers and peace be upon him) making faith a deed, is that we should increase our faith upon our faith, and that is by increasing the righteous deeds that are the cause of strengthening faith, and the opposite is the opposite. So evil deeds, sins, and disobedience are the cause of the weakening of this faith, and it may weaken upon weakness until the matter ends with this faith dying and its possessor losing it. We ask Allah (Mighty and Majestic) to inspire us with guidance and to strengthen our faith.