There are bad priests in all forms of religion.

Yet they say mass.

Of course, very often the people know that they are bad.
Do you think that the mass is less efficacious for the salvation of those who attend it, provided that they themselves pray with the same earnestness ?" "No; certainly not.

For otherwise it would be necessary that the people should ascertain whether the priest is in a state of grace every time he celebrates; and since their salvation would then, depend upon that, they would be committing a sin if they did not examine the relative morality of different priests and select the most saintly one." "Well then, so much the more is it indifferent whether the inanimate vessels we use are chiselled by a saint or an unbeliever.

Their use sanctifies them, not the moral goodness of the artist.