5 We have received grace and apostleship through Him to bring about the obedience of faith among all the nations, on behalf of His name,6 including yourselves who also belong to Jesus Christ by calling.
The best proof of your being born is that you are now alive. If I meet you on the street, I will 10 times out of 10 believe that you were born. 34 years ago this day, I was born. While the 34 years part may require proof to verify, the being born part is pretty self-evident. While I may need a receipt of my birth to verify the time and place, the fact that I was born goes unchallenged.
The best proof of your being re-born from above by the Spirit of Grace in Christ is that you are now alive in His Spirit. If I watch you actively and unrepentantly participating in darkness, I may be concerned as to whether you are, in fact, re-born. I could be wrong. But could you be wrong? Does anyone get to tell you that you are wrong? Do you ever believe you're wrong?
Do you agree with God?
What happens when you and God disagree?
These are great gauges for determining the validity of one’s claims to regeneration.
Faith by grace saves.
Faith by grace obeys.