What to know
Your friend is responding to one of two shocking statements: that God would become flesh, and/or that God would lower himself to experience death. Our Muslim friends often respond first by saying this is impossible. He or she likely doesn’t believe that becoming a man is impossible for God in the sense that his power is too limited (although you should probably begin here regardless). Oftentimes, our friends believe that the physical existence of Christ and his death go against the character of God. This question is about whether or not a holy God would humble (and humiliate) himself by eating, sweating, using the bathroom, living as a baby, etc. ... Begin by asking questions to try to understand what your friend really feels and thinks in specific terms.
What to say
Ask your friend what he or she wouldn’t do for their child. How low is too low? Explore this question in order to land in this central truth: We can’t out-love God. Read Luke 11:11-13 together. Next, read 1 John 4:19. Jesus said that if we, who are evil, know how to give good gifts, how much more our Father in Heaven? In the Holy Book, it’s also said that if we think that we know how to love, it’s because God showed us what love is. We may feel like we’re exalting God by saying that humility is beneath him…But in reality, this demeans him. This is to say that humans can love and give and sacrifice more than God. That would be a heresy. God is the author of love, and any human image of love is only a small image of who he is. Continue this discussion by reading these passages:
Ezekiel 34 and John 10. We see God announce that a day is coming when he himself will come to shepherd his flock. Then we see Jesus announce that he is that Shepherd. The emphasis in these passages is the desire and power of God to save.
Exodus 40, John 1, 2 Corinthians 5:1-10. The presence of God appears to the people in the tabernacle that Moses built. Later, this same term is used to talk about Jesus: the phrase "he made his dwelling among us" echoes the terminology used to describe the glory of God resting in a tent, or tabernacle. The concept of a body as a tent is seen again in 2 Corinthians 5. A study of these passages will help your friend understand that God has always desired to dwell among his people; but this has always happened according to his wisdom. King Solomon rightly said, "Not even the highest heavens can contain you!" And yet God, in his power, created a body as a tent. Jesus is the tabernacle for God to dwell on earth. Note: Many Muslims express disgust at the physical body of Jesus by focusing on the fact that Jesus ate and drank. They may tell you that they're opposed to this belief, but are often reluctant to say why. This opposition is to the idea that God, if truly incarnated as Jesus, would use the bathroom. This is discussed in greater detail in a later post. Within this topic, honor your friend's recognition of the holiness of God. If you sense it's appropriate, consider discussing the way that God forever changed the spiritual concepts of "clean" and "unclean" forever (Matthew 15 and Isaiah 6).