J.M.J. "167. Since Mary alone has crushed all heresies, as we are told by the Church under the guidance of the Holy Spirit (Office of B.V.M.), a devoted servant of hers will never fall into formal heresy or error, though critics may contest this. He may very well err materially, mistaking lies for truth or an evil spirit for a good one, but he will be less likely to do this than others. Sooner or later he will discover his error and will not go on stubbornly believing and maintaining what he mistakenly thought was the truth.
"168. Whoever then wishes to advance along the road to holiness and be sure of encountering the true Christ, without fear of the illusions which afflict many devout people, should take up with valiant heart and willing spirit this devotion to Mary which perhaps he had not previously heard about. Even if it is new to him, let him enter upon this excellent way which I am now revealing to him. 'I will show you a more excellent way.'
"It was opened up by Jesus Christ, the Incarnate Wisdom. He is our one and only Head, and we, his members, cannot go wrong in following Him. It is a smooth way made easy by the fullness of grace, the unction of the Holy Spirit. In our progress along this road, we do not weaken or turn back. It is a quick way and leads us to Jesus in a short time. It is a perfect way without mud or dust or any vileness of sin. Finally, it is a reliable way, for it is direct and sure, having no turnings to right or left but leading us straight to Jesus and to life eternal.
"Let us then take this road and travel along it night and day until we arrive at the fullness of the age of Jesus Christ."
--Saint Louis Marie Grignion de Montfort, Treatise on True Devotion to the Blessed Virgin, 167-168.