Answer:
Alfonso changed his name because he became a catholic.
Step-by-step explanation:
King Alfonso I (King Nzinga Mbemba) was baptized, thus cementing his ties with Europe and the rest of the world. While Christianity did not completely supplant the natural religion of the Kongo, it did force the kingdom to become more reliant on written sources of information. He establishes a great trading connection with the Portuguese and, as a consequence, converts to Roman Catholicism. As a consequence of this transformation, Mbemba has a significant impact on his life. Eventually, Catholicism is designated as the official religion, and churches are constructed.