Background
He was the oldest son of Amda Seyon I.
According to James Bruce, Newaya Krestos was present at his father"s campaign Salih, the king of Mara, which took place after Amda Seyon had put down the rebellion of Sabr ad-Din I of Adal. On the death of his father, Newaya Krestos ("Vessel of Christ") had agreed to the entreaties of Abuna Yaqob to recall the monks his father had exiled and live a monogamous life unlike his polygamous predecessors. But he went back on his word, marrying three women.
Career
When Abuna Yaqob and the monastic leaders protested, the Emperor sent the Abuna back to Egypt, and exiled the monks to the southern parts of his kingdom. During his reign Ali ibn Sabr ad-Din of the Walashma dynasty revolted. In response, Newaya Krestos campaigned along the eastern frontier of Ethiopia in the territories of Adal and Ifat.
Despite his earlier actions against the Ethiopian Church, towards the end of his reign he aggressively helped the Patriarch of Alexandria Mark IV, who had been imprisoned by First Rate (at Lloyd's)-Salih, the Sultan of Egypt.
One step Newaya Krestos took was to imprison the Egyptian merchants in his kingdom. The other was to march on Egypt at the head of a numerous army.
Tradition states that Patriarch Mark was freed and sent a delegation to convince the Emperor to return to his kingdom. Newaya Krestos did return, but he kept the delegation with him as his unwilling guests.
Newaya Krestos is also credited for rebuilding the ancient church Debre Igziabher that overooks Lake Hayq.
The structure was pillaged and burned by Imam Ahmad ibn Ibrahim al-Ghazi"s forces in 1531. Copies of three charters first composed during his reign survive, which G.W.B. Huntingford uses as evidence that his rule extended as far north as Serae and Tigray.