Gregory VII and Muslims

Chris over at the Veritas blog has an interesting comment about a recent piece over at Catholic and Enjoying It concerning an excerpt from the letter of Pope Gregory VII, pope from 1073-1085 AD, to the Muslim King Al-Nasir of Mauretania, which is this:

We and you must show in a special way to the other nations an example of this charity, for we believe and confess one God, although in different ways. Many of the Roman nobility, informed by us of this grace granted to you by God, greatly admire your goodness and virtues.

There are many who have, in recent years, accused our very own Pope John Paul II of indifferentism and universalism because of his friendly relations with Muslims, considering it more of a modern phenomenon. These individuals are simply mistaken. While understanding that the fullness of God's revelation was given in Jesus Christ, and the fullness of that revealed teaching subsisting within the Catholic Church, affirming all that is true and holy in non-Christian religions is, of course, consistent with Catholic teaching, as noted most specifically in the Vatican II document Nostra Aetate:

[The Church] regards with sincere reverence those ways of conduct and of life, those precepts and teachings which, though differing in many aspects from the ones she holds and sets forth, nonetheless often reflect a ray of that Truth which enlightens all men. Indeed, she proclaims, and ever must proclaim Christ "the way, the truth, and the life" (John 14:6), in whom men may find the fullness of religious life, in whom God has reconciled all things to Himself.

Nostra Aetate also quotes Gregory's letter:

[Muslims] adore the one God, living and subsisting in Himself; merciful and all-powerful, the Creator of heaven and earth...

Of course, as I am in most things that pertain to the historical teaching and practice of our faith, I am very interested in reading the whole of the letter from which this snip was taken, but I can't find it online right now.