My pleasure.
"the union of the believer with Jesus Christ which is inseparable"
Actually we can return to our vomit:
2Pt:2 20 "For if, flying from the pollutions of the world, through the knowledge of our Lord and Saviour Jesus Christ, they be again entangled in them and overcome: their latter state is become unto them worse than the former. 21 For it had been better for them not to have known the way of justice than, after they have known it, to turn back from that holy commandment which was delivered to them. 22 For, that of the true proverb has happened to them: The dog is returned to his vomit; and: The sow that was washed to her wallowing in the mire." (DRV)
return to sin, yes, but overpower God, no.
God is omniscient and very well knew before we came to Him, every sin we would ever commit in the future. He still, in His perfect righteousness and justice, was able to bestow by grace our regenerated human spirit in us.
Likewise, regarding His power. We don’t have the ability or power to remove ourselves from the regenerate spirit.
2ndPeter well describes one situation as a consequence of man having eaten from the tree of knowledge of good and evil.
The old man, the natural man doesn’t know of anything of the human spirit prior to faith alone in Christ alone. Once regenerated in the human spirit, positionally sanctified, set apart, He is free to work in us furthering our knowledge of Him. Indeed if we return to the ‘vomit’, we are in a worse state than before as our sense of perfect justice demanded by perfect righteousness, causes us to fear retribution for our unrighteousness.
It isn’t until we return to God on His terms, that we fully understand He isn’t bound to judge us for that sin, rather all judgment for that sin occurred on the Cross when each and every sin of mankind, past, present and future was imputed upon our Lord and Savior Christ Jesus.
Through faith in Him, now His righteousness is imputed to the believer, just as righteousness was imputed to our Lord and Savior Christ Jesus for His faith in the Father, while in Hypostatic Union, and even after a human spiritual death on the Cross as the perfect sacrifice for all mankind.