Many believe that the Holy Father, by his kissing of the Koran, and Vatican II have taught that all religions worship the one true God to a greater or lesser degree, and that Muslims are included in the plan of salvation and thus should not be evangelized. This is in fact not the case.
The Catechism, working from Vatican II's "Nostra Aetate," does say that, "the plan of salvation also includes those who acknowledge the Creator, in the first place among whom are the Muslims. These profess to hold the faith of Abraham, and together with us adore one Merciful God, mankind's judge in the last day."
This is a carefully worded statement. It does not actually say that Muslims believe in Abraham's faith, but only that they profess to hold the faith of Abraham.
Professing and possessing are two different things: Certainly there are many more Christians who profess Christ than there are people who actually live for him. Nowhere does the Catechism say that Muslims are not eligible for the salvation that is in Christ, or that the Gospel should not be preached to them.
Great point, Pyro.