Plenty of intelligent people become Catholic. But I don’t think intelligence gives someone an advantage when it comes to spiritual things. Coming to God is not a purely intellectual process, because a person can know God exists but still refuse to worship him. Maybe if God were simply a concept, it would be an intellectual matter. But since God is a person, and God is love, then it’s also a matter of the heart.
Sin actually blinds us to truth, because sin involves choosing something that’s not true or not right. It’s like if someone fakes their credentials and becomes a doctor without being qualified. What do they think they have, and what do they really have? They blind themselves to the fact that they’re not really a doctor and haven’t accomplished anything good or worthy. They know it deep down, but they ignore it. So it’s not that they aren’t intelligent enough to realize it, but they choose to ignore it. That’s what I mean when I say that coming to God is not really a matter of intelligence.