As it happens, according to mainstream Islamic interpretations of Sharia, proselytizing Muslims is a capital offence. In fact, it is mentioned as far back as the so-called Pact of Omar, which Muslim doctrinaires still quote from, and which delineates what non-Muslims (it was first made with Christians in Syria) must—and must not—do to safeguard their blood.
(meforum.org)(Candid) Although the protections afforded Jews and Christians by Islamic law were, in many ways, ahead of their time, this grace, such as it was, had its limits. According to the Pact of Umar, which defined the relationship between the Peoples of the Book,
[Christians, Jews, and Zoroastrians] shall not build, in our cities or in their neighborhood, new monasteries, Churches, convents, or monks’ cells, nor shall we repair, by day or by night, such of them as fall in ruins or are situated in the quarters of the Muslims.