Based on my understanding that's impossible. It's like you're asking if someone is put in front of the sun and doesn't feel warm then can he say I'm still cold?
The manner of light that Islam or truth for that matter offers, is just like the sun.
Having that said there are no guarantees that what one reads is true Islam. Muslims are split into two major sects (Shias and Sunnis) and then between them are many more sects.
So if a person meets true Islam and doesn't feel it, I say that's impossible. But if you just want to be hypothetical. Then yeah Allah doesn't blame us for not understanding and he won't enter hell.
Yet again Allah has blessed us with wisdom. If that wisdom isn't good enough to help us find out right from wrong then what good is it for?! Similarly he's blessed us with Quran and instructions from The 14 infallibles. If the guidance and light provided by them isn't enough then again it's considered low quality work from Allah and his apostles. But such a conclusion is wrong.
If the person has got his Islam from bad sources (books, instructors) ie he hasn't seen the sun truly then yeah very much Allah treat him differently. But I'm on board that God/Allah didn't make us creators with ever unanswerable doubts. He made us curious but then has given us opportunities to find answers.
In Islam we have three groups of people.
- Believers (مومنین)
- Unguided/Misguided (ضُلّال / مستضعفین)
- Disbelievers (کفار)
Disbelievers are lesser than the other two combined.
Additionally while the Islam offered today isn't as good as the Islam offered when the prophet of Islam, Prophet Muhammad (PBUH), seal of messengers was present and living it. Today you have to learn Islam from a multitude of bad scholars and a very few good scholars, yet at the same time access to Islam, forums that answer every question is much easier.