This is a short story involving a robot janitor who wishes to become a Christian, written by Mike Resnick. About 12 thousand words, or an hour long read at a leisurely pace.
Indestructible fugitive robot liberates his kindred.
About 10 thousand words or a 50 minute read.
Indestructible telepathic robots strike and become recognized as equals. About 6.5 thousand words, or 30 minutes.