Sh. Ibn al-ʿUthaymīn رَحِمَهُ اللهُ said, “If the pre-requisites of excommunication are fulfilled with respect to him, it is permissible to declare disbelief on him specifically, and if we did not do that, the description of apostasy would never be applied to anyone. Thus, he is treated as an apostate in this world with respect to the rulings of this worldly life. As for the rulings of the Hereafter, they are mentioned in a general sense and not specifically, this is why Ahl al-Sunnah say,

‘We do not testify for anyone [as being in] Paradise nor the Fire except for the one whom the Prophet ﷺ testified.’

Likewise, we say, whoever fasts Ramaḍān out of faith and expectation, his coming and previous sins are forgiven, however we do not declare this for a specific person. This is because the ruling connected to the descriptions are not applied to individuals except when the pre-requisites of its application are fulfilled and its preventative factors are removed.”

Source: Majmūʿ Fatāwá wa Rasāʾil Faḍīlat al-Shaykh Muḥammad b. Ṣāliḥ al-ʿUthaymīn, 2:125, no. 219.