Marcos 14:31

Jesus’ reply should have caused Peter to realize his weakness and seek help. Instead he dug in his heels and virtually told Jesus that he would die to prove Him wrong. He kept affirming excessively (Gr. ekperissos, used only here in the New Testament) that he would definitely not deny Jesus. Peter did not know how weak he was, a problem most disciples of Jesus share with him. He would have to learn the hard way, through failure. Peter led the other disciples in denying that they would deny Jesus. [Note: W. N. Clarke, "Commentary on the Gospel of Mark," in An American Commentary, p. 214.] Later he denied Jesus with the same vehemence with which he professed that he would not.

This pericope is a strong warning for all disciples. When facing persecution for one’s allegiance to Jesus, one should not trust in the strength of his or her commitment. He or she should trust in God who can supply the grace needed to remain faithful (cf. Mark 9:14-29).