Expositor's Bible Commentary Commentary John 14:29

"And now I have told you before it come to pass, that, when it is come to pass, ye may believe." — John 14:29 (ASV)

Throughout the gospel the necessity of believing is emphasized (1:50; 3:12, 15–16; 4:21, 41; et al.). Jesus insisted that acceptance of his person is pivotal to spiritual experience. The particular form of “believe” used here by Jesus indicates the beginning of an action, not its continuation. After the previous statements that the disciples had believed (1:50; 2:11; 6:69), such a construction seems inconsistent. Nevertheless the final arrest and death that they would soon witness would undoubtedly shake their faith to its foundations, and Jesus wished to prepare them for the strain this crisis would place on them.