VATICAN CITY, DEC. 2, 2001 ( On the first day of Advent, John Paul II reminded Christians that preparation for Christmas is "not the vain awaiting of a faceless god" but "concrete trust" in a God who loves us.

When the Holy Father met with thousands of pilgrims gathered in St. Peter´s Square to pray the Angelus, he invited Christians to reflect over the next few weeks "on the mystery of Christ, a mystery that is always new and that time cannot exhaust."

"Christ is the Alpha and the Omega, the beginning and the end," he said today. "Thanks to him, the history of humanity proceeds as a pilgrimage toward the fulfillment of the Kingdom, which he himself inaugurated with his incarnation and victory over sin and death."

"Because of this, Advent is synonymous with hope: not the vain awaiting of a faceless god, but concrete and certain trust in the return of him who has already visited us, of the Spouse who has sealed a pact of eternal alliance with humanity in his blood," the Holy Father clarified.

The hope of Advent should stimulate vigilance, "the characteristic virtue of this singular liturgical time," John Paul II continued.

"Vigilance in prayer, fostered by a loving expectation; vigilance in the dynamics of concrete charity, aware that the Kingdom of God comes close wherever men learn to live as brothers," the Pontiff said.

He summarized this time of waiting by quoting the prophet Isaiah, heard in the day´s liturgy: "In days to come, the mountain of the Lord´s house shall be established as the highest mountain. ... All nations shall stream toward it. ... They shall beat their swords into plowshares and their spears into pruning hooks. One nation shall not raise the sword against another, nor shall they train for war again."

John Paul II concluded by reminding the faithful that the Marian feast of the Immaculate Conception will be celebrated next Saturday.

"May she guide us on this way, helping every man and nation to look toward the mountain of the Lord, image of the final triumph of Christ and the advent of his Kingdom of peace," the Pope said.