Honesty is not enough to be known by Jesus.
Luke 13:24 “Exert yourselves vigorously to get in through the narrow door, because many, I tell you, will seek to get in but will not be able. 25 When the householder gets up and locks the door, you will stand outside knocking at the door, saying, ‘Lord, open to us.’ But in answer he will say to you: ‘I do not know where you are from.’ 26 Then you will start saying, ‘We ate and drank in your presence, and you taught in our main streets.’ 27 But he will say to you, ‘I do not know where you are from. Get away from me, all you workers of unrighteousness!’
Matt. 7:21 “Not everyone saying to me, ‘Lord, Lord,’ will enter into the Kingdom of the heavens, but only the one doing the will of my Father who is in the heavens will. 22 Many will say to me in that day: ‘Lord, Lord, did we not prophesy in your name, and expel demons in your name, and perform many powerful works in your name?’ 23 And then I will declare to them: ‘I never knew you! Get away from me, you workers of lawlessness!’
If the person's faith is based on religious falsehoods, he has never really been associated with the God of truth, nor with his holy spirit. It's like pretending you know someone and living an imaginary relationship with him, but in real life, that person has no idea you exist. Nor can a person know what is involved in following Jesus if his idea about it is wrong
... like when a traveler goes to another country and without realizing it he violates the Law there, because what he did is not punishable in his own country but in that country it is. Even so he has to answer to the law of the country he is visiting... he should have known what was illegal in that country before visiting it.