I think what he meant was that moral ideas, like freedom, can only be grounded in religious ones. That is, a non-religious community has no basis for absolute morality. Therefore, "freedom" and "rights" could be defined in any way the majority desires. The implication being that, without religious folk, America would abandon moral ideas like freedom or rights. That doesn't mean that you personally would be forced to believe in any particular religious system.
I don't agree. I think that being a decent human being can be part of a humanist perspective, and that one can do so simply because they're a decent human beings. Rescuing a trapped animal or putting a band-aid on a sad kid that hurt themselves makes you feel good in an indefinable way because that's part of being a good human being. No other species has evolved to the level of intellect and self-awareness that they can help or heal others, even those not of their species, just for the sake of doing so. We're the only species that evolved beyond basic competition (at least most of the time) and that's what makes us special. And we're the only species that can contemplate its own awareness.
As for why one does good things, I don't need arcane rituals that humans have come up with to explain why, or to enforce why. I just do it.
When I look at the modern holy books, I see the system that's in vogue now. I know that it hasn't existed very long, in fact, about two thousand years. Before that, there were other belief systems that persisted far longer. The Greco-Roman pantheon. The Egyptian pantheon. The Sumerian.
Like it or not, a harsh bit of reality is what is considered religion today, the dominant religions, Christianity, Judaism, Islam, Buddhism and Hinduism, in 3000 years, might be regarded as we regard the Egyptian pantheon. Times will change, ideas will change. There will be something completely new that people call religion, likely. The Egyptians, the Sumerians, the Greeks were devout to their religions, too. Amun and Isis were real to the Egyptians and were prayed to. The Norse peoples, likewise. Odin was real to them. Native Americans were, and some still are. Now they're regarded as mythology. Before what we call prehistory, there were many other religions, the details of which have been lost. Some Neanderthals put flowers and objects in the graves of their dead. What were their rituals that inspired them to do that? Viewed from that perspective, of the vastness of time and how many things have come before, it looks a bit different to me.
YMMV.
(And there's a vast gulf between nihilistic atheists, which are depressing and pretty pointless, and those who simply believe in the human potential to continually evolve, without bounds, using what we've done with philosophy and science thus far as evidence.)
