No (see below) .So if they change their ID cards to "believe in God Almighty" they are free to marry Muslims and register it at the catatan sipil?
The "Believe in God Almighty" in a KTP means a religion/belief other than Islam, Protestant Christianity, Catholicism, Hinduism, Buddhism, and Confucianism .
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According to https://www.hukumonline.com/klinik/a/nikah-beda-agama-cl290/ , in 2023 the Indonesian Supreme Court decided that the Court does not grant applications for registration of marriages between members of different religions and beliefs .
