with the proviso, however, that mere abandonment does not in itself render a person an unbeliever, for it amounts to practical—not doctrinal—disbelief, as Ibn al-Qayyim has already explained.
This is precisely how Shaykh al-Islam Ibn Taymiyyah—may Allah have mercy on him—treated the relevant proofs. In his Majmūʿ al-Fatāwā (22/48) he was asked about someone who neglects the prayer without any excuse: is he still a Muslim in that condition?
He—may Allah have mercy on him—gave a lengthy, knowledge-filled answer, but what matters for our discussion is the following excerpt. After stating that, according to the majority of scholars—Mālik, al-Shāfiʿī, and Aḥmad—the abandoner of prayer is to be executed, he said:
“If he remains steadfast until he is killed, is he executed as an apostate unbeliever, or as an open sinner like the other grave sinners among the Muslims? There are two well-known opinions, both reported as separate narrations from Aḥmad. Now, if he inwardly acknowledges the prayer and believes it to be obligatory, it is inconceivable that he would persist in leaving it until he is killed without praying. Such behavior is unknown among human beings and their customary dispositions. For this reason it has never occurred in Islam; no case is known of someone who admits that prayer is obligatory, is told, ‘If you do not pray, we will kill you,’ yet still stubbornly refuses to pray while confessing its obligation. This has never happened in Islam.” ⦗43⦘