Ayn Rand was an atheist.
And Socrates was a pagan - it didn’t and doesn’t stop him from being one of the founders of Western thought and philosophy.
And Thomas Jefferson was a Deist (at best) - that doesn’t stop him from being a highly influential founding father whose wisdom is cited and will be cited by lovers of liberty until the end of human history.
If one is only to adopt useful and correct ideas from those who share the same religious tradition - one will live in a very shallow and dim world.
Not any more.
Atheists may be wrong about the existence of God (at least in my view they are wrong), but that doesn’t mean they are wrong about everything.
And Milton Friedman was an agnostic. That does not lessen my respect of his economic theories.