Matthew 17:17-18

Jesus’ rebuke recalls Moses’ words to Israel in Deuteronomy 32:5; Deuteronomy 32:20. Unbelief characterized the generation of Jews that had rejected Jesus, and now it marked His disciples to a lesser extent. Their failure to believe stemmed from moral failure to recognize the truth rather than from lack of evidence, as the combination of "perverse" and "unbelieving" makes clear (cf. Philippians 2:15). The disciples, too, were slow to believe, slower than they should have been. Jesus’ two rhetorical questions expressed frustration and criticism.

"Jesus has accepted that he will be rejected by the official leadership of Israel (Matthew 16:21), but to find himself let down even by his own disciples evokes a rare moment of human emotion on the part of the Son of God." [Note: Ibid., p. 661.]