Literally the only thing debated is at what point the lump of cells turns into a life. That is the only discussion that drives the moral argument. Unless someone is foolish enough to say the lump of cells should be left alone too, because then I don't want you searching for a way to get rid of cancer in your relatives. Tumors = group of cells. Egg + sperm = group of cells UNTIL a certain point in time. That point in time is the only thing that should be debated.