Reference: Fataawa Ramadhaan – Volume 1, Page 51, Fatwa No.18
Question: Is a person who leaves off fasting due to laziness and heedlessness like the one that leaves off prayer in the respect that he is a disbeliever?
Response: The one that leaves off fasting out of heedlessness and laziness is not a disbeliever. That is because the basic rule is that a person remains upon his Islaam until sufficient proof shows that he is outside Islaam. There is no proof that the person that leaves off fasting is outside the fold of Islaam if he left it due to laziness and heedlessness. This is not the same as prayer because the texts from the Book of Allaah and the Sunnah of His Messenger (sal-Allaahu ‘alayhi wa sallam) and the sayings of the companions all show that the person that leaves off praying through heedlessness and laziness is a disbeliever.
‘Abdullaah ibn Shaqeeq said: “…the companions of the Messenger of Allaah (sal-Allaahu ‘alayhi wa sallam) didn’t consider as disbelief the leaving off of any actions except prayer”.
It is obligatory to call this person who is neglecting to fast due to laziness and heedlessness to fast. If he refuses he should be banished until he fasts.