I am what you called a non practicing Roman Catholic, I was schooled in a Catholic School from nursery up to college, but the order who ran our school does not give a shit about this from my time way back up to now (Our country's priests and nuns are more interested in politics which they absolutely knew nothing about
:D)
The term Avada Kedavra or the killing curse in Harry Potter is of Aramaic origin (the tongue of Jesus) which means "let the thing be destroyed" BUT it is used to heal or cure illness and the "thing" is the illness. JK Rowling used it negatively.