Only a very small number of people are going to become religious after learning about it in RE so consigning it to history is going to do very little in making religion history.
RE is almost as much about learning different cultures as it is religious specifically, and it useful when you consider most people will have a good understating of one religion anyway. Teaching people about others usually makes people less isolationist and more inclusive. Ignorance is a scurge in many walks of life.
except in nearly all students eyes its a waste of time, a mark/grade they cant use, just like pse/general studies and is simply an obstacle to them passing their other subjects.
so they wont pay attention they wont learn anything and you almost certainly end up with substandard teachers.
its a waste of time and should be dropped.