1 sn Jesus tells the disciples that he has told them all these things before they happen, so that when they do happen the disciples may believe. This does not mean they had not believed prior to this time; over and over the author has affirmed that they have (cf. 2:11). But when they see these things happen, their level of trust in Jesus will increase and their concept of who he is will expand. The confession of Thomas in 20:28 is representative of this increased understanding of who Jesus is. Cf. John 13:19.