Final answer:
Frumentius, a Syrian missionary, played a key role in converting King Ezana and thereby bringing Christianity to the kingdom of Aksum, marking the kingdom's shift from polytheism to Christianity.
Step-by-step explanation:
Christianity was brought to the African kingdom of Aksum by the Syrian missionary Frumentius. He was shipwrecked on the Eritrean coast, later brought to the royal court, and became a tutor to King Ezana who was at that time a devout polytheist. Frumentius converted King Ezana to Christianity following which he was sent to Alexandria to request the appointment of a bishop for Ethiopia. He was subsequently appointed by Athanasius, the bishop of Alexandria, and took the name "Selama." This was pivotal in establishing the Christian Kingdom of Aksum, with King Ezana replacing Aksumite coinage imagery with a Christian cross, signifying the kingdom's conversion from polytheism to Christianity. The strategic location of Aksum also contributed to the spread of Christianity, with its connections to various trade routes and the Roman Empire potentially influencing its religious orientation.