Why I'm not Catholic

"Ask many Protestants today why they are not Roman Catholic and they may refer to `something about Mary and the saints.' However, for the Reformers, the heart of the problem was the ... sufficiency of Christ the Mediator for sinners. Are we justified by grace alone ... in Christ alone, or by grace and our merits, faith and our works, Christ and the intercession of Mary and the saints." - Michael Horton