Is it illegal to (steal) someone elses wireless internet?

So my net is getting shut off because I'm not getting enough hours at work to pay the tv/net/phone bill. My neighbor, who is "disabled" for having a "back problem" but yet still does heavy construction work on the side has wireless. I said that because I have no moral qualms about stealing from someone who lives off of my paycheck. Anyway, I know he has an unsecured network. Moral reasons aside, is it illegal to leech off of his network? Thanks