This study is to find out how Islam and positive law respond to interfaith marriages in Indonesia. This study uses a literature study research method, by examining the rules in the Qur'an and hadith, studies of scholars and the Marriage Law of the Republic of Indonesia No. 1 of 1974 along with related laws and regulations. UUUP article 2 paragraph (1): "Marriage is legal if it is carried out according to the law of each religion and belief", and article 8 letter (f): Marriage is prohibited between two people who have a relationship that by their religion or other applicable regulations, forbidden to marry          In this formulation there is no marriage outside the law of each religion and belief. As for the Presidential Instruction of the Republic of Indonesia Number 1 of 1991 concerning the Compilation of Islamic Law, Article 4: "Marriage is legal, if it is carried out according to Islamic law in accordance with article 2 paragraph (1) of Law Number 1 of 1974 concerning Marriage. In the Indonesian jurisdiction, it must be carried out with those who have the same belief, that is, they both follow the same religion, meaning that interfaith marriages are not allowed to be carried out and if they are forced to hold interfaith marriages, it means that the marriage is not recognized or invalid because it will violate the law. Thus, interfaith marriages cannot be legalized in Indonesia.