The Bible has the same authority of Jesus Christ himself. It is literally the words of Jesus Christ.
Those who truly trust in Christ will listen to his words.
The Bible says in John chapter 10 verse 25 to 27,
Jesus answered them,
I told you, and ye believe not, the works that I do in my Father's name, they bear witness of me.
But ye believe not because ye are not of my sheep, as I said unto you.
My sheep hear my voice, and I know them, and they follow me.
John chapter 8 verse 47 says,
He that is of God heareth God's words, ye therefore hear them not,
because ye are not of God.
So if you admit anybody who claims to be saved,
and yet they don't listen at all to God's word, then they're not of God. It's simple.
That is the reason why,
that is the reason given here in John chapter 8
by Jesus of why the Pharisees refused to believe, because they're not of God.
John chapter 8 verse 37 says,
To this end was I born, and for this cause came I into the world,
that I should bear witness unto the truth.
Every one that is of the truth heareth my voice.
First John chapter 4 verse 6,
We are of God. He that knoweth God heareth us.
He that is not of God heareth not us.
Hereby know we the spirit of truth and the spirit of error.
So those with the spirit of truth will listen to the preaching of God's word.
Now, hypothetically, if a man says, I trust in Christ,
and yet you show him a doctrine in the Bible and he refuses to believe it,
even when it's crystal clear, then he's not saved.
Now, there are some things which,
some things which people believe which might not be as clear in the Bible,
which might not be as clearly taught.
For example, interpretation of prophecy.
To say someone isn't saved because they have a,
they believe in a different timeline for the end times than you do is ridiculous,
because those timelines are usually pieced together
through careful examination of hundreds of passages and verses all throughout the Bible.
There's no one passage in the Bible that just lists everything out in order of when it's going to happen clearly.
So that's not something which you should really argue about.
But when it's clear doctrines which are taught over and over again
in every single book of the Bible, that's different.