I don’t know about what Bible says… but I know a certain commander who’d give up his replicator rations just so a certain Captain can have coffee. Also… he knows all too well to give her coffee first thing in the morning…

I think Kathryn gave up cream and suger in her coffee after losing her father and Justin. It was a form of self punishment, by giving up things that made her life more comfortable, more sweeter was the way she thought that she could remember of how it was before and how it was after the tragic incident. She wasn't doing this out to pay her penance, but to berate herself, to remember that it was her fault.

and then Admiral Janeway gave up coffee... to tea. We all know how much Captain Janeway loved coffee. How many times did we here ...

''Computer, coffee....black'.

Admiral Janeway said she didn't know why she gave up coffee... but she did it because she needed to punish herself, giving up the luxury of coffee, the taste and smell of it is a reminder of DQ, of crew they lost, and she thinks it is her fault. and mainly because of losing Chakotay. he returned to Earth but died within a month. And Janeway blamed herself for his death more than any other occured in DQ, more than Seven's.

I think she couldn't get out of her mind how much her coffee reminds of him.... and it was too painful to the point that she gave it up. she gave up the thing she used for years in Voyager. She gave up that luxury to punish herself.