Protestants believe that it is wrong to enter the religious life as a monk or a nun. They say religious should be out saving lost souls, and they are wasting their time when they could be out helping their fellow man. So what about it?
First of all, many monks and nuns are "out in the world." Many are missionaries, or charity workers, or teachers and nurses. Secondly, prayer is probably the most important aspect of the Christian life. We can have one specialize in almost every area in life–evangelism, preaching, etc.–so why is it wrong to have a group devoted entirely to prayer? It is only by prayer that God gives men the grace to say confess "Jesus is Lord." If prayer is the most important aspect of Christian living, what is wrong with devoting one's self to it continuously? "The prayers of a righteous man are powerful in its effects" (Jas. 5:16). Monks and nuns do assist others, and in every way, through their prayers and penances. Thirdly, there is the Biblical example of the prophetess Anna: "There was also a certain prophetess, Anna by name . . . She never left the temple, worshiping day and night in fasting and prayer." (Luke 2:36-37). And finally, it was monasticism that preserved many valuable writings, including the Bible, during the Dark Ages.
Some Protestants (although few in number) still lend credence to the story of Maria Monk and similar stories of ex-nuns who escaped convents. Maria Monk, for instance, wrote "The Awful Disclosures of the Hotel Dieu Nunnery", which purported to relate her experiences as a nun in a convent in Montreal. According to Monk, nuns were to be obedient to the priests, which included having intercourse with them. There were tunnels linking the rectories and convents, where priests and nuns would get together for this reason. In these tunnels was a grave in which the bodies of babies born out of these unions were thrown. Nuns were regularly imprisoned for various reasons, and Monk even tells the tale of a nun who was killed by a group of priests.
Actually, the book was not even written by Maria Monk, but by a number of Protestants, one of whom was a Protestant minister that she had run off with. According to her mother, Maria Monk suffered a brain injury as a young girl, and ever since then, had wild fantasies. Apparently, Monk's only contact with the Catholic Church was in a Catholic-run asylum for a short time, in which she got pregnant and was asked to leave. The people of Montreal, both Protestant and Catholic, were outraged at Maria Monk's claims, knowing that what she wrote was not true. Shortly after the publication of "The Awful Disclosures", a Protestant by the name of William Stone examined the convent, and after an interview with Maria Monk, concluded she had never even been to the convent, and that her story was a fabrication. In ensuing years, Monk ran off with another man, got pregnant again, and died in prison on a charge of pickpocketing. No one without ignorance or prejudice today takes the claims of Maria Monk seriously. Her story was never proven, and neither were similar stories of ex-nuns. Only the most gullible and prejudiced of people have or do put any stock in such claims.