What you wrote is quite obscure.
Much more popular is "believe and do not doubt".
Also: Jesus' response to Apostle Thomas after his resurrection from the dead is recited during every Easter mass: "Because you have seen me, you have believed; blessed are those who have not seen and yet have believed."
Yes, on the surface the religion is the textbook antithesis of free thought. And yet I think my friend was getting at something deeper I can't quite pin down easily. Maybe it was just a lucky combination of aristocrat philosophers justifying their pursuits? Then there was the Enlightenment thing...