خلاصه
این هنوز مسلمان است ولی ایمانش ناقص است
ایمان با اطاعت میرود بالا و با عدم اطاعت میرود پایین
What is the ruling on someone who believes in the oneness of God but is negligent in performing some obligatory acts?
This person is considered to have deficient faith. Similarly, someone who commits some sins has their faith diminished according to the Ahl al-Sunnah wal-Jama'ah. They say that faith consists of speech, action, and belief, and it increases with obedience and decreases with disobedience. Examples of this include failing to fast during Ramadan without a valid excuse or skipping some days of fasting.
This is a major sin that diminishes and weakens one's faith. Some scholars even consider such a person to be a disbeliever.
However, the correct view is that such a person is not considered a disbeliever as long as they acknowledge the obligation of fasting, but have missed some days due to negligence and laziness.
Similarly, delaying the payment of Zakat beyond its due time out of negligence or failing to pay it is a sin and indicates weak faith. Some scholars consider abandoning Zakat as an act of disbelief.
Likewise, severing ties of kinship or being disobedient to one's parents is a deficiency and weakness in faith, and the same applies to other sins.
As for abandoning prayer, it contradicts faith and necessitates apostasy, even if the person does not deny its obligation, according to the more correct view of the scholars. This is based on the saying of the Prophet Muhammad (peace be upon him): "The head of the matter is Islam, its pillar is prayer, and its highest peak is Jihad in the way of Allah." And his saying: "The covenant that distinguishes between us and them is prayer; whoever abandons it has committed disbelief," as well as other hadiths that indicate this.