JOEL - The Missionaries job is to find those people who have been touched by the spirit in a way that makes them ready to listen to the gospel message. They should always be willing to talk with anyone the first time and teach them the first of a series of discussions about the Church. But they have been counciled to not spend their valuable time in fruitless discussions with people who only want to argue points of doctrine or who do not really show any potential interest in becoming a member of the Church. If you are sincerely interested there is no reason why they should deny you the opportunity to learn about it. The picking and choosing part of it usually comes after the missionaries have talked with someone a couple of times first. If the person does not seem really interested or sincere about becoming a member then they might move on. Missionaries are always eager to talk to anyone about the church at least once.