Excerpts from the ‘Jurisprudence of Worship’
By Shaykh Muhammad ibn Saalih ibn Uthaymeen رحمه الله تعالى

Question: Oh Noble Shaykh, What is the ruling of one that prays when Ramadān comes, however when he has broken away from Ramadān, he breaks away from Salāh (The Prayer) and Saûm (Fasting)?

Answer:
That which is made apparent to me from the evidences is that the one who abandons the Salāh does not become a disbeliever except if his abandonment (of Salāh) is in totality. As for the one who prays and then leaves it, he prays sometimes and he does not other times, that which has been made apparent to me from the evidences is that he does not become disbelieving for that.

By the statement of The Prophet: Muhammad ﷺ:
“The covenant that is between us (the Muslims) and them (the disbelievers) is the Salāh (the prayer). So whomever abandons it has verily disbelieved.”
The one who abandons it meaning the Salāh (in totality) has disbelieved”.¹

And by his ﷺ statement:
“Between a man and between Shirk (polytheism) and Kufur (disbelief) is abandoning the Salāh (the prayer)”.²

However, for the man who does not pray or fast except in the month of Ramadān, I am doubtful of his faith. For verily if he was a true believer he would pray in Ramadān and in other times as well. As for his state where he does not know his Lord except in the month of Ramadān, I am doubtful of his faith. However I do not rule that he is a disbeliever, rather I refrain from ruling upon him and his affair is with Allāh عز وجل.

¹Related by Tirmidhi- The Book of Belief [Number 2621]
²Related by Muslim- The Book of Belief [Number 82]

Translated by: Abu Uwāis, Muhammad Abdullahi Elmi