Okay, I'm sorry... I mean it; I'm really sorry, I apologize, I mean no harm... but I'm the sometimes-crochety old son of an English teacher and I keep seeing something that just keeps poking me in a sensitive spot.
"Alter" is a verb meaning "to change."
"Altar" is a flat space, usually a table or other raised platform, used for religious/spiritual ritual.
I know it's only one letter, and that "a" and "e" are kissin' cousins.... but the education geek in me just wouldn't let it go. I apologize again, and thank you all for your understanding of my weakness. <:-}