This one started spreading after the Boston Globe blew the lid off the Catholic Church's priests raping children scandal several years ago, and now it's ubiquitous. But still dead wrong.
Or it will be if they just agree to throw more human sacrifices on the alter:Sacrifices, human and otherwise, are made on altars. There is no such noun as alter. There is, however, a verb to alter that means to change.
Help Your Grammar Nazi alter this common misuse by confining your sacrifices and your worship to the altar.