The ruling on relying on faith in the heart alone without action

Also, a sister in Islam from Baghdad, Iraq, asks: Is faith in the heart sufficient for a person to be a Muslim, even if he is far from prayer, fasting, and zakah?
Answer: Faith in the heart alone is not sufficient; it does not suffice in place of prayer and other acts. It is obligatory for him to believe with his heart that Allah is One, having no partner, and that He is his Lord and Creator. It is obligatory for him to single Him out for worship, (Glorified and Exalted is He), and to believe in the Messenger Muhammad (peace and blessings be upon him) as the true Messenger of Allah to all people. All of this is necessary; this is the foundation and basis of the religion.
However, prayer and the other matters of the religion are also required alongside this. If he prays, he has fulfilled what is required of him. If he does not pray, he commits disbelief, because abandoning prayer is disbelief. As for zakah, fasting, Hajj, and the other matters, if he believes in them and that they are obligatory, but he is lax in performing them, he does not commit disbelief for that; rather, he is a sinner, and his faith is weak and deficient. This is because faith increases and decreases; faith increases through obedience and righteous deeds, and decreases through sins. As for prayer specifically, abandoning it is major disbelief according to a group of scholars, and this is the most correct of the scholars' opinions. This is unlike the other acts of worship, such as zakah, fasting, and Hajj, where abandoning them is not disbelief according to the correct view—meaning major disbelief—but rather a deficiency in faith and weakness in faith. Abandoning zakah is a great major sin, abandoning fasting is a great major sin, and abandoning Hajj while having the ability is a great major sin. However, it does not become major disbelief if he believes that zakah is a right, that fasting is a right, and that Hajj with the ability is a right, and he does not lie about it or deny its obligation, but rather he is lax in practice. In that case, he does not become a disbeliever for that according to the correct view.
As for prayer, if he abandons it, he commits major disbelief according to the most correct of the scholars' opinions, may we seek refuge in Allah, if he abandons it entirely. As for the two testimonies that Allah is the Lord of all and the God of all, and that there is no deity but Him—meaning, no one is worshipped with truth but Him—and the testimony that Muhammad is the Messenger of Allah, these two testimonies are the foundation of the religion and the basis of the faith. A group of scholars, and this is the opinion of the majority of jurists, held that a person is a Muslim by them, even if he does not pray, provided he believes in the obligation of prayer, fasting, Hajj, and so on, but does not act on it and is lax. The majority of jurists held that he does not commit major disbelief if he abandons those things; he remains a Muslim who is a sinner, in danger of entering the Fire, but he is not declared a disbeliever for that.
A group of scholars held that abandoning prayer is major disbelief, and this is the stronger opinion, as mentioned previously, and it is the most correct. This is based on the saying of the Prophet (peace and blessings be upon him) ; and his saying (peace and blessings be upon him): as mentioned in the answer to a previous question.
Therefore, one should be careful about this. As for the other obligatory matters of the religion, such as zakah, fasting, Hajj, and the like, if a believer in Allah and His Messenger believes in their obligation and does not deny their obligation, but may be lax in performing them, this does not become major disbelief. Rather, it becomes a deficiency in faith and weakness in faith, and he becomes a sinner deserving of entering the Fire and the anger of Allah, unless Allah forgives him, (Glorified and Exalted is He). This is based on His saying, the Exalted: [Al-Nisa: 48]. He made what is less than shirk subject to the will of Allah, so it is known thereby that sins are subject to the will of Allah and do not make one a disbeliever with major disbelief. Rather, one becomes a sinner and one with weak faith. Yes.