One with diagnosed OCD gets constant thoughts of kufr. He becomes unsure if he said it, so he repents for apostasy and does ghusl in a cycle. He wants to ignore it, but is afraid if he really did kufr and just forgot/ignored it, and if he doesn't repent, he will die a kaffir. How to reply to this?

Ustadh AbdulAziz al-Haqqan

What he is doing is already forbidden, so if he truly fears Allah he should ignore it. Anyway top priority is that he seeks a trustworthy Muslim doctor.