Less common than they were once upon a time, stationary pulpits are typically large, and often built in place; they are monstrosities which are used in churches with an emphasis on tradition, ritual, and preaching. The pulpit becomes the centerpiece of the church and it represents the position of authority granted to the person speaking from that pulpit.
Traditionally stationary pulpits are occupied only by the leader of the church. Other speakers use small lecterns to the side.
In the case of a stationary pulpit, the pulpit is to the preacher what the Resolute Desk is to the President of the United States, and it represents power.
More common in modern churches, portable pulpits vary in size but tend to be made of lightweight materials and might even be constructed of smaller pieces in order to ensure portability. This sort of pulpit makes the stage in a church more versatile for multi-purpose use.
Multiple studies have shown that the single worst fear among most humans, even larger than death or dismemberment, is the fear of public speaking. Those fears diminish with the number of people on the stage with us, or with obstructions or barriers between ourselves and those to whom we speak.
For many preachers, the pulpit serves as just such a psychological protection device. A protective pulpit may be stationary or portable, but the thing they have in common is that they cover the majority of the preacher's body.
A preacher who prefers this sort of pulpit tends to stand in place during her sermons and will often use minimal hand gestures to emphasize her points. This is by far, the most common type of pulpit used in churches today.
Invisible pulpits are not truly invisible, but they may as well be. They serve as a stand on which a preacher may hold his notes and/or his Bible, but such a pulpit might be as non-intrusive as a music stand (and often times are indeed music stands).
It offers no symbol of authority and no protection for the preacher, who tends to move around the stage as he speaks. This is the sort of pulpit typically used by an extroverted sort of preacher who is comfortable within himself and his flock.
He stands as his own authority and feels no need for backup. Some pulpits of this nature might be made of clear plexiglass, or of thin pedestals on legs.
Though not as common as the protective pulpit, they come in a variety of materials and designs.