Teshuva in Responsa I
A Responsum on the status of a Jewish convert to another faith, by R. Eliezer b. Isaac the Great who lived in Mainz at the beginning of the eleventh century: A kohen became converted to a Christianity of his own free will,
eventually becoming a Christian priest. Later he repented and returned to his Jewish fold. Do he and his children have the privileges of a kohen?
The reply is that there is no question whatever that the children are fit and cannot be disqualified because of their father’s sin. As for the man himself, he is entitled to be called up to the Torah first, but he may not recite the priestly blessing. The reason for the latter ruling is that the priestly blessing is compared to ministering in the Temple, (Menachot 109a-b) from which he is disqualified.
Can we apply this concept of loss of status to everyone, or is it specific to a Kohen who committed such a terrible sin?