Crypto-Islam
Crypto-Islam is the secret adherence to Islam while publicly professing to be of another faith; people who practice crypto-Islam are referred to as "crypto-Muslims". The word has mainly been used in reference to Spanish Muslims during the Inquisition.Some historic examples include Ahmad ibn Qasim Al-Hajarī, 16th-century crypto-Muslim from Spain who authored a book recounting how he organized his escape from Spain to Morocco, and also including a refutation of the Catholic opinions about Jesus. The books also included details about how crypto-Muslims lived in Spain. He later became Ambassador of Morocco to Spain.
There are claims that Armah, who ruled the Kingdom of Aksum and gave refuge to early Muslim converts, was a crypto-Muslim.