What to know Clean and unclean, "Halal and Haram," are huge topics in Islam. In Christianity, we may have lost sight of how the Gospel of Jesus speaks into this worldview and vocabulary*. One major issue many Muslims take with the Deity of Jesus is surprisingly physical in nature: It's the concern that if Jesus ate food, he would have to defecate. In a Halal / Haram worldview, which gives high focus to being clean on Judgment Day, it is unthinkable that God would lower himself to such an "impure" act. More than unthinkable, in Islam, it's evidence: the Gospel can't be true because it's against the character of God to become unclean.
What to say
Read Matthew 15:1-20 together (also recorded in Mark 7:1-22).
What did Jesus say makes us unclean?
What would Jesus say about this Gospel-concern and question?
Listen as your friend responds. It's possible that the physical act of consuming food, and the "unclean" physical need that accompanies this, is not the primary concern. He or she may be able to reconcile that "holiness" is not defiled by what goes in the mouth. Their question instead might be, "Isn't that disgraceful" (shameful)?
At this point, we're not speaking into a Halal/ Haram worldview. We're speaking into a Shame / Honor worldview.
Many Muslims believe that God would not lower himself for his creation...that to lower himself would be to go against one of the most fundamental attributes of God: his glory. Within that lens, the resistance and rejection of the Gospel is much greater than the topic of food and excrement. It's about how far God would be willing to go for humanity. Listen to your friend and asking good questions. It's of highest value for them to hear themselves say the words: that God "would not" do this. If or when a person states this, you can engage with clarity.
Read Luke 6:40 and John 13:16, with Matthew 7:9-11.
How far would a human father go to save his child? How far is too far? What humiliation is too great? Listen and discuss.
Can a human love more than God? Can a human's morality or goodness be above God's?
If "we who are evil" can do good...what is God like? Is any act of Love too great for him?
Is it reverent to believe that a human can surpass God in willingness to sacrifice for another?
Read Romans 5:6-8 together. The message of Jesus is this: that although a human might be willing to die for a good man, God has done something far greater. He took on human flesh in order to die for us, while we were still sinners. The Creator of the galaxies existed as the Father in Heaven and al-Masih on the cross in order to die for his creation. It is the greatest, and most radical, wonderful, and pure act of Love any mind could ever conceive.
End with reading 1 Corinthians 2:9-10, together with John 1, 1 John 1, and 1 John 4 (full chapters.) Pray for your friend as they take in the Word of God.
*This video ("Holiness," made by The Bible Project,) may help illuminate the concept of clean and unclean to you. Take a moment to listen to the Gospel spoken into this paradigm before you begin.