The natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned.
That a person must be born again to understand the things of God, I agree.
But when Jesus raised Lazarus so that they might believe, was belief a gift he gave them after regeneration, or belief something they were responsible for?
When Jesus said, “I said this on account of the people standing around, that they may believe that you sent me”, was Jesus lying? Was he mocking them? Was he claiming that he would give them belief?
Or did he do miracles so that they might believe, and those who rejected him would be responsible for their unbelief?
Jesus said, “You refuse to come to me that you may have life”, not, “You do not have life, so you refuse to come”!
What was that you were saying about the natural man...?
"Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost" -- Titus 3:5
Even our "work of faith" is God-given. Unless a person has been born by the Holy Spirit, the Bible remains a puzzle to him, and salvation just a riddle.