Here's a short and striking passage from Father Philippe about how the Apocalypse (the first of St John's writings), changed his way of seeing the Church at a time when the Church was experiencing weakness.
The Church must live out the Mystery of ChristWhen John receives this revelation [the Apocalypse] he understands that the Church of Christ, born at the Cross, will have to live everything that Jesus lived. As Church of Christ she must follow Jesus, “follow the Lamb wherever He goes,” (Ap. 14, 4) and thus live everything the Lamb lived. She must live the Agony, the Cross, the Sepulchre. From this moment on, John looks upon the Church with completely new eyes. Prior to this revelation - as the French exegete Andre Feuillet points out - John had a perhaps critical view of the Church. As the last remaining apostle, John saw the first generation after the death of the apostles. Now after the death of the apostles, of those who knew Jesus and lived with Him, the Church inevitably experienced a period of weakening. John witnessed this weakening, a weakening that was hard for him to bear. It is then tha the Apocalypse revealed to him how intimately the Church is to be bound to the fate of Christ and with this revelation, John came to love the Church in an entirely new manner.
Fr. M.-D. Philippe, o.p., Wherever He Goes, p.72