The Catholic Encyclopedia has this text on the topic of the Magisterium, and the problems of Protestant approaches to scripture:
In a similar way they show that they cannot dispense with a teaching authority, a Divinely authorized living magistracy for the solution of controversies arising among themselves and of which the Bible itself was often the occasion. Indeed experience proved that each man found in the Bible his own ideas, as was said by one of the earliest reforming sectarians: "Hic liber est in quo quaerit sua dogmata quisque, invenit et pariter dogmata quisque sua." One man found the Real Presence, another a purely symbolic presence, another some sort of efficacious presence. The exercise of free inquiry with regard to Biblical texts led to endless disputes, to doctrinal anarchy, and eventually to the denial of all dogma.
Have there been any cases where Roman Catholics opposed bible study or other ecumenical worship in a public setting (say state-run schools) on the basis of this doctrine?