You are not in a family because of what you believe..
Its totally who you are that determines physical relationship..
And according to Jesus, spiritual relationship..
"You MUST be born again" -Jesus
NOT you "must" be enlightened intellectually..
Nicodemus was unclear also, as you are(seem to be)..
Some people are "thick".. (like Peter or Thomas)..
Its not what you believe its who you are that counts..
Belief is a nebulous thing.. sophistry and semantics..
WHO ARE YOU?.. Is the question...
Would the non believer be a member of this family?
John 3:18 He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God.
"You MUST be born again" -Jesus NOT you "must" be enlightened intellectually..
The belief Jesus is telling us we must have is not intellectual enlightenment you are referring to.
Luke 18:17 Assuredly, I say to you, whoever does not receive the kingdom of God as a little child will by no means enter it.