They might be busy with work and school and don’t think about religious things at all.
They call themselves “spiritual but not religious” but to me, that’s still religious. They just like a different word better.
They might be agnostic, meaning “They don’t know”.
Or maybe they are atheist and choose to say “I don’t believe in God”. They might even think that “religion is wrong” and fight it.
So the answer is “sometimes but not always”.