Etymology of Deadline

I am like a child, I hear other things when people say things but do something else.  Today,  I googled the word deadline to figure out why I have a hard time meeting them for a lot of things.  The first definition I got when looking on Webster’s definition was  “a line drawn within or around a prison that a prisoner passes at the risk of being shot.”  I immediately thought about the movie “Life” starring Eddie Murphy and Martin Lawrence.  I have never liked the word dead and that is what triggered me to look up the word.  The word dead is so finite, so rough, so harsh sounding to me and believing in God I believe that when our Earthly bodies expire our soul’s return to heaven.