Complex sentence: Israel's religious authorities--the only entities authorized to perform weddings in Israel--are prohibited from marrying couples unless both partners share the same religion, therefore interfaith couples can be married only if one of the partners converts to the religion of the other.
Split into simpler sentences: Israel's religious authorities--the only entities authorized to perform weddings in Israel--are prohibited from marrying couples unless both partners share the same religion. Therefore interfaith couples can be legally married in Israel only if one of the partners converts to the religion of the other.