1 Corinthians 15:10 But by the grace of God I am what I am, and his grace toward me was not in vain. On the contrary, I worked harder than any of them, though it was not I, but the grace of God that is with me.
If we look only to the words “I worked harder than any of them” you might sense ego because of how Paul places I first in that thought.
Allow me if you would to reframe the context of the comment in relation to the issue of self worth. We are sinners saved by grace, but sinners none the less. Paul struggled desperately to erase his past, one who persecuted the church and had been widely known as an enemy of Christ.
The flesh does not stop being flesh just because we accept Christ.
Galatians 5:17 For the desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh, for these are opposed to each other, to keep you from doing the things you want to do.
The flesh uses our past to constantly tell us we are not worthy. It is difficult to forget our past behaviors and difficult to let go of our past in order to allow God to use us to do His will.
Shame caused Adam to hide his face from God and all Adam did was eat one bite of fruit. Paul did things that none of the other apostles had to live down. Paul, as Saul, held the robes of the men stoning Stephen to death as he urged them to do so. Paul, then Saul, got letters of commendation from the Sanhedrin to arrest followers of Christ.
Acts 9:26 And when he had come to Jerusalem, he attempted to join the disciples. And they were all afraid of him, for they did not believe that he was a disciple.
What we often overlook is that it took Paul three years before he came back to serve God. During those years God was erasing the phrase “I am not worthy” from his mind.