Matthew 15:28 (LEB)
Then Jesus answered and said to her, “O woman, your faith is great!
Let it be done for you as you [will].”
The Greek here is similar to what Jesus says later in Matthew 26 in His prayer to the Father about letting this cup of the cross pass from Him.
Matthew 26:42 (NKJV) Jesus said, “Your will be done.”
For some reason, the translators, which almost always translates ‘thelo’ and ‘thelema’ (Strongs 2307 and 2309) as “will” puts Jesus words to the Canaanite woman as “desire.” (Maybe bias?) Nothing wrong with the word “desire,” but it might hide the fact it is the same meaning that Jesus uses in His own prayer. And thus, to make sure we do not miss the impact of this we will use the same word of “will” for both verses. It is the same used in the Lord’s prayer, “Your Will be done on earth.”
Jesus referring to the broad category of God’s plan to only minister to the Jews, not the gentiles, says by implication that it is “not God’s will” to heal her daughter. Jesus even goes so far as to argue that it is ethically wrong to take what belongs to someone, and then give it to another person. As Vincent Cheung states, she “asserts an argument of faith.” Jesus, God in the flesh, God’s Will in the flesh, the most God centered man who ever lived, then does a 180 change about what God’s will is, by ignoring God’s will and says, “woman, your will be done,” instead. Jesus says, “let man’s will be done,” in essence.
When it comes to the promises of God, when people have faith, Jesus kept over and over, affirming the will of man. This is not some overly makeup guy, sitting in a gold chair on TBN. This was God Himself, in direct verbal revelation, affirming the “will of man,” when man engages God’s promise in faith. Your theology must deal with this.
When James says in chapter one of his letter that if you have faith you will be given wisdom, he does not say, “only if it is God’s will.” Rather, he says it is man’s accountability to get wisdom from God, if you lack it. And if you failed to get the wisdom, then the accountability is on “your” lack of faith, not the will of God. That is, if you have faith, in your trial of lack of wisdom, then God’s response is that the will of man (“Lord, I want wisdom”) is to be done on earth. James says the same thing about healing and forgiveness in chapter 5. When man’s faith engages the promises of God, the God Himself affirms “let man’s will be done.”
For more see on this topic, see the essay by Vincent Cheung. (Healing: The Will of Man)
(I am not affiliated or with Vincent Cheung.)