Notice how Paul’s treating his opponents in Acts 22:1-21. He speaks to them respectfully, referring to them using the honorary titles “brothers and fathers.” He’s speaking their language. He commends them for their zeal for God’s law. He personally and publicly relates to their opposition to Christianity. He too once persecuted Christians.
Paul can treat his opponents this way because he remembers the Gospel. He remembers what he’s been saved from. The Gospel reminds us that all of us have sinned and fallen short of the glory of God. The Gospel teaches us that God loved the world so much He sent His only Son to die in our place. If you’re a Christian, you weren’t born that way. You didn’t become one because you were smart enough to “figure it out.” Your relationship with God was bought and paid for with blood.
Paul was able to treat his opponents with such gentleness because he continually reminded himself of this Gospel. He put it this way in 1 Timothy 1:15—The saying is trustworthy and deserving of full acceptance, that Christ Jesus came into the world to save sinners, of whom I am the foremost.
Dietrich Bonhoeffer put it this way: “To forego self-conceit and to associate with the lowly means, in all soberness and without mincing the matter, to consider oneself the greatest of sinners. This arouses all the resistance of the natural man, but also that of the self-confident Christian. It sounds like an exaggeration, like an untruth. Yet even Paul said of himself that he was the foremost of sinners . . . .
If my sinfulness appears to me to be in any way smaller or less detestable in comparison with the sins of others, I am still not recognizing my sinfulness at all. My sin is of necessity the worst, the most grievous, the most reprehensible. Brotherly love will find any number of extenuations for the sins of others; only for my sin is there no apology whatsoever. Therefore my sin is the worst. He who would serve his brother in the fellowship must sink all the way down to these depths of humility. How can I possibly serve another person in unfeigned humility if I seriously regard his sinfulness as worse than my own?” He then quotes the Medieval theologian Thomas a Kempis who wrote, "Never think that thou hast made any progress till thou look upon thyself as inferior to all"[i]
[i] Dietrich Bonhoeffer, Life Together: The Classic Exploration of Christian in Community, (New York, HarperOne, 1954), 96-97. Emphasis added.