I have always thought that Paul understood grace much more than many others because of the depth of his sin from persecuting Jesus and His followers. I have always imagined Paul being deeply grieved by what he had done and his understanding of grace stemming from this. But I was studying Galatians & Acts where it tells of Paul going to Jerusalem to once and for all get a decision about whether gentiles had to convert to Judaism and be circumcised. He brought the issue before Peter and the apostles and they deliberated over whether righteousness was from faith or from something we must do. The decision was that faith alone restores you to God and that this is it in order to experience salvation.
When I was studying this it occurred to me that Paul had grown up becoming the perfect Jew, following all the law, being groomed to be the best, zealously persecuting those he felt were wrong and forcefully obeying the rules. When Christ came to him and set him on a new path on the road to Damascus, he encountered God and it completely revolutionized who he was. I realized that his understanding of grace came from feeling the burden of the law ("doing & performance") being lifted from off of him. Suddenly the weight was gone and he understood Jesus saying that His yoke is easy and His burden is light.
So instead of it just being sorrow and repentance for his sin (which I am sure he felt deeply) being the basis of his understanding, Paul understood grace and freedom because he personally experienced it. He no longer suffered and groaned under the law. No wonder he was so passionate about not putting the yoke of slavery on gentile believers. He knew that his own people were breaking under the burden and refused to lay that burden on others.
I am a gentile believer and I have not been put under the law but under grace. I can glimpse a bit of Paul's passion for grace and understand even more how Christ has set me free and blessed me beyond my wildest imaginations! What a thought! Praise You God for Your wondrous blessings and love! I will be meditating on this verse.
Galatians 5:1 Amplified
IN [this] freedom Christ has made us free [and completely liberated us]; stand fast then, and do not be hampered and held ensnared and submit again to a yoke of slavery [which you have once put off].