Is it true that in his book Crossing the Threshold of Hope, the pope said that everybody will be saved and no one will go to hell?
Absolutely not. In fact, the pope states that one problem in the modern Church is that priests do not preach enough about hell. The pope states, “To a certain degree man does get lost; so too do preachers, catechists, teachers; and as a result, they no longer have the courage to preach the threat of hell. And perhaps even those who listen to them have stopped being afraid of hell. In fact, people of our time have become insensitive to the Last Things” (183).
Concerning the reality of hell, John Paul II says,
The problem of hell has always disturbed great thinkers in the Church, beginning with Origen and continuing in our time with Mikhail Bulgakov and Hans Urs von Baltha-sar. In point of fact, the ancient councils rejected the theory of the “finalapokatastasis,” according to which the world would be regenerated after destruction and every creature would be saved, a theory which abolished hell. But the problem remains. Can God, who has loved man so much, permit the man who rejects him to be condemned to eternal torment? And yet, the words of Christ are unequivocal. In Matthew’s Gospel he speaks clearly of those who will go to eternal punishment (cf. Mt 25:46). Who will these be? The Church has never made any pronouncement in this regard. This is a mystery, truly inscrutable, which embraces the holiness of God and the conscience of man. (185-186)