I agree with most all you said except this part about Paul. Paul was not talking about his life during his entire christian walk when he said that. He was describing the failure of a person who uses will power to serve God by keeping laws in contrast to someone who lives by the Spirit.
It's not as long as we live we are vexed to failure. It's as long as we exert will power to serve God without any faith in reliance on His Spirit that we are vexed for failure.
Paul put himself in the shoes of someone keeping law but not walking after the Spirit's help, and it's easy to confuse his words. We think he always struggled all his life. No. That was only a description of what it's like to use will power.
We know this because we learn that Paul said he DIED when he attempted to keep law (
Rom 7:9-10). But he said we LIVE by relying on the Spirit instead of lawkeeping.
Romans 7:9-10 KJV For I was alive without the law once: but when the commandment came, sin revived, and I died. (10) And the commandment, which was ordained to life, I found to be unto death.
Romans 8:13 KJV For if ye live after the flesh, ye shall die: but if ye through the Spirit do mortify the deeds of the body, ye shall live.
When he used will power by attempting to keep laws, he died.
When we walk after the flesh we die.
Same thing. Synonymous terms.
And Paul knew how to walk after the Spirit.
Grace is also interpreted as DIVINE EMPOWERMENT!!!