Sure, and Ramsay argues that a mortgage is fine. His contention is that ideally you wouldn't need to have any debt. So once your retirement is on track, you would pay down the mortgage because it's no longer needed.

I disagree with him, but that's probably because I'm very disciplined and have never had an issue where I have more non-mortgage debt than cash on hand. In fact, I was very nervous about my mortgage debt, so I aggressively saved after getting a house to build up investments so they would exceed my mortgage (I can now theoretically pay it off if I liquidate my retirement accounts). I have never financed a car (my cars are both 15+ years old), never paid credit card interest, and never needed a personal loan. I have maintained an emergency fund since I was 16 (didn't call it that until my late 20s). I see debt as a tool, if I can get lower interest debt than I can make with guaranteed returns, I consider it foolish to not take it. In fact, I have a few thousand in 0% credit card debt right now because I refuse to pay it back until the promo is about up.

That said, many people have a problem handling debt, so if that's you, Ramsay's advice is perfect. I actually like listening to his show, and I recommend him all the time, despite disagreeing with him on practically everything. He offers a very structured program that works for a lot of people, and that's way better than trying something perhaps mathematically better but relies on discipline.