This is a fantastic thread as it's something that comes up often. By refusing to say we'll pray for someone, as agnostics or atheists, are we being like Lois Lanes father....letting our pride in our rightess get in the way of comforting a person in need? Or are ]we being hypocrites and taking the easy way out by saying yes to keep them happy, whilst in reality doing nothing?
For me, it depends on the circumstance and my relationship with the person. If I am very close to them I think I would take the time to explain my beliefs, but make sure I was there for them in body and spirit. If they were very Ill, or elderly, I would probably say to them I will do anything you ask and can I help practically too - that way allowing them to be comforted by the thought I will pray for them.
I'm sorry I'm so wishy washy Co Co, I guess Its just about putting the person first, and not letting ourselves be like the self righteous JW in LoisLanes example.