If I were to compile a list titled "Common Catholic Misconceptions of the Catholic Faith," near the top would have to be this Catholic misconception about the nature of sanctity:
The saints are to be considered perfect in their earthly lives, to such an extent that all that they did while in this life is considered right, just, and necessary for Catholics to imitate in their own lives.
We see this misconception play out in the multitude of ecclesial dramas in the Church today, from the radical Traditionalists who use St. Paul as justification for criticizing current popes, styling doing so to be "resisting Peter to the face" (misunderstanding the limits of papal critique) to the radical Progressives who lionize St. Therese of Lisieux as a champion of women's ordination (misunderstanding Therese's desire for the priesthood). Even in the middle of these two extremes, ordinary Catholics sometimes ask about the extreme penances of the saints (e.g., St. Rose of Lima's disfigurement of her face, St. Aloysius Gonzaga's severe fasts), wondering if their sanctity means that all Catholics must take up such austerities in order to become saints themselves. Or some Catholics may engage in objectively uncharitable acts, such as treating others abusively, and rationalize it by saying, "Well, St. John the Baptist called the Pharisees 'a brood of vipers'! Why can't I?"
Just today the apologists received a review copy of a children's book on the life of St. Louis IX of France titled Saint Louis and the Last Crusade. Written in the 1950s by Margaret Ann Hubbard, the book has been republished as part of Ignatius Press's Vision Books series on the saints—an excellent line of saints novels for children that first introduced me, when I was a new Catholic, to the lives of the saints. While thumbing through this novel, I remembered again the Catholic tendency to glorify reported behavior in a saint that would be considered problematic if replicated today by a Christian.
(Nota bene: Please keep in mind as you read ahead that I am not criticizing St. Louis nor the Vision Books series. I am criticizing one portrayal of St. Louis by a Catholic hagiographer who wrote during the mid-20th century.)
When discussing St. Louis's marriage to Marguerite of Provence, the book depicts Louis as not considering his new wife to be his queen—she was to be his wife, and support him in being a good king, but in his mind his mother was Queen of France. He did not defend his wife to his mother and he did not trust his wife's judgment. Even France apparently had a higher claim to his love and loyalty than did Marguerite. According to Hubbard, Louis had Marguerite's wedding band inscribed with the motto "God, France, and Marguerite." Marguerite was expected to join in his austerities (such as fasting on bread and water on Fridays, and declining to wear nice clothing on any occasion but state functions), his charitable deeds (washing the feet of beggars), and his renunciation of the comforts of their position. Whether or not any or all of these acts were meritorious, the issue is with the idea of expecting another person, even one's wife, to suppress her own personality in favor of conforming herself to one's own spiritual ideal.
You might ask then why such a man could be considered holy.
For one thing, St. Louis was a product of his time. The Christian understanding of marriage has developed a great deal since the Middle Ages. Even though sins that would make medieval Christians such as St. Louis rightly gasp in horror have become commonplace in Christian marriage—and thereby demonstrate that the medievals had advantages over us in their practice of their faith—the doctrines undergirding the sacrament of matrimony, Christian conscience, and human freedom have matured over the course of those centuries.
Another issue is that saints become perfect only at the end of their lives. During the course of their lives, even while striving for sanctity, they can misunderstand and can sin as surely, though perhaps not as readily, as the rest of us. A priest once told me that a friend of his, who has served as postulator for a well-known American on the road to sainthood, was told by those experienced in the canonization process to focus most of his attention on the last fifteen years of the saintly candidate's life. While due consideration had to be given to the whole, it was the last fifteen years that would be most determinative. (And, in certain cases, like that of Jacques Fesch, who reverted to his Catholic Faith while awaiting execution for the murder of a police officer, only the last couple of years before death can be considered at any length.)
Finally, and most importantly, holiness is not synonymous with perfection. To be holy means to be "set apart for God." The holy person accepts the universal call to dedicate one's whole life to God and strives to live his life according to that ideal by the graces he receives from God and to the best of his own ability. He may make mistakes, but he is always open to correction. He may sin, but he always repents and seeks reconciliation. He chooses God and is chosen by God. We imitate his virtues, but we do not necessarily mimic his actions. As Dorothy Day once observed:
I have since heard a priest friend of ours remark gloomily that one could go to hell imitating the imperfections of the saints.
We do not become saints by copying the saints. We become saints by loving God as they did.