This is interesting...I have never ever doubted being birthed in the Spirit....Yet!!.....I have doubted God’s word, even though he delivered it to my heart on something I am going to receive from him, that was 30 yrs ago....at the beginning when he revealed this to me, my mind was in turmoil, it was such a battle of the mind...but,God has the victory because, my faith has brought me through to this place I am now at, my head has now lined up with my heart on what I am about to receive and I have no doubt whatsoever that I will receive it...how about that for a turn around....God gets all the Glory......my faith just keeps getting stronger and stronger..Praise God!
Going to Heaven is assured as soon as you gave God your Faith in Christ.
But the knowledge that is the renewed mind, has to be learned.
We have to learn who we are are in Christ..
"working out your salvation" isn't about "trying to stay saved"......its about getting the revelation of being made "the righteousness of God in Christ".
You can always hear it when someone has this Light.
They stop talking about SIN SIN SIN SIN SIN SIN SIN.
And start talking about "what God has provided for me"....
And when they really are full of the knowledge of the Truth, they'll talk about the Cross a lot., as that is the final answer to it all.