Since no one else has replied yet, may I get the ball rolling (to start)?
When you ask about the "type," that could mean several things.
One answer would be: it is a passive sentence. That is, it is another way to say: "Baptism removes original sin."
If you wanted to diagram it using the Reed-Kellogg system, I think that it would be parsed like this:
Original sin = subject.
is removed = verb
by baptism = prepositional phrase that modifies "is removed." It answers the question: How is original sin removed?
Hopefully, someone will draw the diagram and post it for us.
HAVE A NICE DAY!