1Co 15:9-10, 9 For I am the least of the apostles, who am not worthy to be called an apostle, because I persecuted the church of God. 10 But by the grace of God I am what I am, and His grace toward me was not in vain; but I labored more abundantly than they all, yet not I, but the grace of God which was with me.
There is a sense of humility that engulfs believers when they are aware that what they are is not a result of their works or effort. I love the old folks testimony concerning salvation, it tends to sound like this “The Lord saved me on …” compared to our days testimonies that sound like this, ”I accepted or asked Jesus into my heart on…” The difference makes it clear to unbelievers who did what.
With Paul, he wants us to see that it was all God’s doing and he takes zero credit or give it to any man. He was not made through any merits of his own. It was entirely the free favor and sovereign will of God. He says, “I laboured more abundantly than they all” he labored in the word, doctrine, preaching, travelled, wrote, was instrument in converting souls, planted churches, endured hardships and sufferings more than any of the other apostles. But then add a clause, “…Yet not I, but the grace of God which was with me”. He attributes all to the grace of God, and nothing to himself. He is exceedingly careful to magnify the free favor of God, and the gifts of his grace. “It is God that works in you” (Php 2:13; Mat 10:20; Col 1:29).