In To Sanctify the World (Basic, Oct.), Weigel chronicles the history and impact of the Second Vatican Council.

Could you speak to why you call the Second Vatican Council the “most important event in the history of Catholicism since the Council of Trent” in the 16th century?

Whereas the Council of Trent created what we call the counter-reformation church, the Vatican II accelerated the transition into what I have called evangelical Catholicism or what John Paul II called the Catholicism of the “new evangelization”—a church of intense missionary fervor rather than a church of institutional maintenance and self-defense.

What do you see as the council’s legacy?

There were two primary questions the council sought to address: Who are we as human beings, and how should we live together in decency and solidarity? It sought to address the first by lifting up Jesus Christ as the model of the truth about humanity and our dignity and destiny. It rather boldly proposed that the church is the image—or in the council’s language, the “sacrament”—of true human community and the unity of humanity because the Catholic church is genuinely universal. Those are the two big themes that I think put Pope John XXIII’s intentions for the council into focus.

You write about the church’s efforts to lay out a “Christ-centered humanism” to respond to “atheistic humanism.” How do they differ?

Christian humanism does not believe that we are congealed stardust. We’re not a cosmic accident, every human person is an idea in the mind of God. That’s very different from atheistic humanism’s notion that we’re all the result of random biochemical forces. Secondly, Christian humanism says we have an eternal destiny. Death is not the end of the story because the creator of the world and the creator of the human person entered the world’s story as redeemer, making it possible for human beings to live beyond death in a realm of enhanced life. The third difference is that the late 19th and early 20th centuries were full of bad ideas revolving around the notion that human beings cannot live in solidarity with each other; Jews can’t live with gentiles. Germans can’t live with Russians. Black people can’t live with white people. The Catholic church says that is not true, that humanity in all of its magnificent diversity is a single creation of a benign and redeeming creator. Therefore, we ought to be able to discern ways to live together in decency and solidarity.

What do the claims of the Second Vatican Council mean for people who are not Catholic?

Vatican II challenges us to lift our sights, to stop demeaning ourselves as preprogrammed creatures who are bound by race, ethnicity, nationality, or religious conviction, or the lack thereof, and to think of ourselves as capable of greatness. “Stop dumbing yourself down,” the church says to everybody. We can do that by meeting Jesus Christ.