Anthrax-laced letters bearing messages that “Allah is great” dominate our headlines. New York continues to dig out the pile of rubble and corpses left there by Mohammed Atta and a gang of killers who left behind copies of the Koran.

These terrorists are clearly outside the mainstream of Islam. But is their something in Islam itself that should worry us?

The Catholic Church, in the Second Vatican Council and since, has proclaimed its deep respect for Islam, and called Catholics to a dialogue with it. To do so, we need to see and celebrate Islam's beauty. But we also need to acknowledge points of vigorous disagreement between the way of Christ and the way of Mohammed.

As Vatican II put it in Nostra Aetate, its Declaration on the Relation of the Church to Non-Christian Religions: The Church “has a high regard for the Muslims, who worship one God, living and subsistent, merciful and omnipotent, the Creator of heaven and earth” (No. 3).

Pope John Paul II, in his book Crossing the Threshold of Hope adds: “As a result of their monotheism believers in Allah are particularly close to us.”

This is the fundamental attitude of Catholics toward Islam: We see profundity in its simple teaching about God and a high moral standard in its call to surrender to his will.

But this isn't the whole story of what we see there.

“Whoever knows the Old and New Testaments, and then reads the Koran, clearly sees the process by which it completely reduces divine Revelation,” writes the Holy Father. “In Islam all the richness of God's self-revelation, which constitutes the heritage of the Old and New Testaments, has definitely been set aside.”

While John Paul notes that some of the “most beautiful names in the human language are given to the God of the Koran,” he adds that, “He is ultimately a God outside of the world, a God who is only Majesty, never Emmanuel, God-with-us.”

In a word: “Islam is not a religion of redemption.”

Islam has “no room” for the Cross, the Resurrection, the Incarnation, he writes. “For this reason not only the theology but also the anthropology of Islam is very distant from Christianity. ”

In our dialogue with Islam we should be moved to see and imitate its beauty — but to reject and mitigate its truncated understanding of man.

What is there to imitate? Among others, the Pope mentions the attitude of those who, “without caring about time or place, fall to their knees and immerse themselves in prayer.” The Focolare Movement and the Sant Egidio Community have embraced Vatican II's call to dialogue with Muslims. Their efforts have borne much fruit. They are open to seeking the good in Islam, and have made many Muslims more open to the redeeming message of the Gospel.

At the same time, the Pope doesn't recommend naivete.

Presciently, he notes that “In [Islamic] countries where fundamentalist movements come to power, human rights and the principle of religious freedom are unfortunately interpreted in a very one-sided way — religious freedom comes to mean freedom to impose on all citizens the 'true religion.’ In these countries the situation of Christians is sometimes terribly disturbing. Fundamentalist attitudes of this nature make reciprocal contacts very difficult. All the same, the Church remains always open to dialogue and cooperation.”

So, what should Catholics think of Islam?

We should see its beauty and think it a very good thing indeed. But it should also remind us of the fundamental difference between Christianity and all other religions.

That's in the Christian conviction that God is love, and that to love is man's most important duty. Only by being true to this central tenet of our faith will Catholics advance.