Leslie M. Grant · Comments on the Gospel of Matthew

Verse 21 however shows that there are different kinds of evil spirits, and this kind required prayer and fasting to expel. This does not deny what He has already said, but further explains it; for prayer is the very expression of dependent faith: in fact it is the positive side of faith; while fasting emphasizes its negative side. That is, faith, while depending on God, also judges every selfish motive. These two things connect with verse 17, for "faithless" indicates lack of confidence in God's Positive power, while "perverse" implies the negative attitude of lack of self-judgment. Indulging ourselves is not the real energy of faith, for it perverts the use of God's gifts merely for personal benefit.