A Misunderstanding?

What was the truth?

This was a question which has a simple answer, but at the same time, it was as complex as a paradox.

The truth should be when someone believes something to be the truth. However, they could also be wrong at the same time because what they believed was the truth could be false as well, and they were beveling a lie their whole life.

When someone corrects that believable truth with solid evidence, that truth will turn into a lie in the same person's mind who believed it to be the truth the very instant it was corrected.

Then even if that person doesn't admit it despite knowing that it was a lie all along, which he believed to be truth, it won't change the fact that the person now knows in his mind that it was a lie.

Yet at the same time, both persons might not know the truth at all, and everything was false, yet they believed it to be truth. So, would this false still be the truth as long as someone wholeheartedly believed it's the truth?