You wrote:
“What might those “reasons” be?”
Sins for which they have not repented.
Christ said men must repent in order to see heaven.
"...except ye repent, ye shall all likewise perish." -- Luke 13:3
Obviously this is a great truth because Christ repeated the declaration two verses later in Luke 13:5.
But you made the comment about Protestants in particular...
VLAD: "If a Protestant goes to hell it is for different reasons."
I assume you believe the words of Christ who called on men to repent of their sins. Protestants believe that.
So what are the "different reasons" Protestants would "go to hell?"