They never come out.

That sounds dreadful, doesn’t it? But when one undertakes to enter upon a permanent state in life, it is intended to be permanent. I have become a Priest, and dreadful to relate, I can never cease to be a Priest. A girl marries a man, and dreadful to relate, she remains married to him. Yet you are wrong. A good many girls do come out of that Convent. Those who enter undergo a long probation before they are finally accepted, and many leave during this period of probation. It is far easier for a girl to come out from the Carmelite Order than it is for one to get into it. Believe me, the doors are opened more easily from the inside than from the outside.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty