What does Matthew 9:29 mean?
A pair of blind men have recognized that Jesus is the Messiah, referring to Him by the name Son of David. They have asked Him to have mercy on them, meaning that they want to receive their sight (Matthew 9:27). Jesus, waiting until He is inside with them, asked if they truly believed in His power to heal—and they responded with an enthusiastic "yes" (Matthew 9:28). Jesus cares deeply that those He heals believe He can heal them.Now Jesus touches their blind eyes and tells them that their faith is the trigger for their miraculous restoration. It's important to understand that these men are not healing themselves, nor is the healing power coming from their faith, itself. The men are healed "according to" their faith, not "by the power of" their belief.
It is Christ's power—the power of God—that restores their sight. Their faith contributes to their healing to the extent that their faith is in Jesus and nothing else. Because He is the object of their faith, they will be healed by Him.