As a Christian I don't think that's always true, and as an atheist I would have rejected it too. Do the majority of people actually think it's always true?
It is especially not required to be honest to people who are actively working against your own health and safety. You are not required to let your captors know you are planning an escape.
That's like a basic survival instinct. It transcends morality. I'd tell people that Jesus really was the son of a god if it meant living to see another day. I'd tell people other lies in order to guarantee I receive life saving drugs.
I feel like the weighting of your statement is off (wrt being controversial); not sacrificing yourself is the norm, and not immoral, while taking the option to sacrifice yourself is noble. As opposed to "Yeah, that guy ran back into the building to try to save the last kid from the fire. It's a shame he died, but he was just doing what was morally required so doesn't deserve any adulation".
Avoiding harm is a moral principle I'm sure many share and there are cases where this conflicts with being honest. If you go down this “you should never lie” you are effectively choosing to do the harm because you prioritise honesty. Maybe that's right in that situation, but you are doing a compromise between ethical principles in either case.
Personally I used to be never-ever-lie dogmatic, but as I've lived my thinking as evolved and I definitely think there exists cases where lying is the more ethical option. However, it's important to me that it's strongly ethically justified and not just something you do because it's the most easy or whatever.
The framing of morality as between prioritizing certain morals over others is only a particular way of viewing it - the consequentialist way. For deontological metaethics, you have something like a categorical imperative.