When someone is baptized, but has no faith, soon enough he will commit a sin from which he baptism will not save him. So, faith is indeed the foundation of our salvation. That faith, incidentally, includes the faith in the sacraments. Bishop Challoner explains is very clearly (see 81).
Do you use a Douay-Rheims Bible, a Douay-Rheims-Challoner Bible, or something else?