A Muslim asked me if God became mortal. I thought this was a good question. But I knew it was an attempt to trap me since Muslims deny that Jesus has two natures: God and man. However, his question cannot be answered with a simple yes or no. We first need to understand a little bit of Christian theology to respond properly.

In one sense, God cannot be mortal because God is the infinite, spiritual being, who is without biological limitations, and who does not change. Therefore, mortality is not part of his nature. However, on the other hand, in Christian theology, we teach that in the single person of Jesus are two distinct natures: the divine and the human. We say that in the person of Jesus, who walked on earth 2000 years ago, there indwelt the divine nature as well as human nature. So we would say that there is a sense in which God became mortal when he joined himself to human flesh. But we must be clear that the divine nature in Christ did not change. It did not become mortal. Mortality is related only to the human nature of Jesus. But again, in the one person of Christ are two distinct natures so in that sense we can say that God became mortal.

Hypostatic Union: Immortal God and mortal man

In Christian theology, there is a doctrine called the hypostatic union.  This doctrine states that within the one person of Christ are two distinct natures: God and man. Verses used to support this would be the following:

Jesus as God	Jesus as Man
He is worshipped (Matt. 2:2, 11, 14:33).	He worshipped the Father (John 17:1-26).
He is prayed to (Acts 7:59).	He prayed to the Father (John 17:1-26).
He is sinless (1 Pet. 2:22, Heb. 4:15).	He was tempted (Matt. 4:1).
He knows all things (John 21:17).	He grew in wisdom (Luke 2:52).
He gives eternal life (John 10:28).	He died (Rom. 5:8).
All the fullness of deity dwells in Him (Col. 2:9).	He has a body of flesh and bones (Luke 24:39).

Communication of the Properties

Furthermore, we also say that Jesus claimed the attributes of both natures. He said he was hungry and thirsty, but he also said he would be with the disciples wherever they would go (Matt. 28:19-20) and that he would also indwell them (John 14:23). These last two proclamations are claims of deity that the single person of Christ applied to himself. So we would say that Jesus claimed the attributes of both humanity and divinity. He can do this because in his personhood are two distinct natures: God and man.

So, when someone asks if God became mortal, then we have to understand there are two senses in which it can be understood. In one sense, we cannot affirm that the divine nature somehow lost its immortal attribute and died. On the other hand, in the doctrine of the hypostatic union (the two natures of Christ), we can see that God joined with human nature in the single person of Jesus. It was only the human nature that was mortal and therefore died on the cross. But because Jesus the man claimed the attributes of both humanity and divinity, in that sense we could say that God became man, that God became mortal.

The Quran as an analogy for mortal and eternal natures

One of the things I will ask a Muslim who denies the possibility of Jesus having two natures is to address the issue of the Quran. Islam teaches at the Quran is divine. It asserts that the Quran is the earthly copy of the divine tablet in heaven and that it was revealed through the prophet Mohammed. Therefore, I point out to them that the Quran is according to them, in a sense, the divine in material form. I then asked the Muslim why that is not possible with a human being.