St. Stephen is a great companion and friend. In earlier times, a person's saint day was a big deal, not quite as big a deal as one's birthday, but a day on which people wished people well, sent them a card, or called them on the phone. St. Stephen's day is also traditionally something like a day for deacons.
The immediate cause of the stoning of this Greek-speaking Jew was his fearless preaching, making him the first Christian to die for the faith:
"'No, you took up the tent of Moloch and the star of (your) god Rephan, the images that you made to worship. So I shall take you into exile beyond Babylon.' Our ancestors had the tent of testimony in the desert just as the One who spoke to Moses directed him to make it according to the pattern he had seen. Our ancestors who inherited it brought it with Joshua when they dispossessed the nations that God drove out from before our ancestors, up to the time of David, who found favor in the sight of God and asked that he might find a dwelling place for the house of Jacob. But Solomon built a house for him. Yet the Most High does not dwell in houses made by human hands. As the prophet says: "The heavens are my throne, the earth is my footstool. What kind of house can you build for me? says the Lord, or what is to be my resting place? Did not my hand make all these things?" You stiff-necked people, uncircumcised in heart and ears, you always oppose the holy Spirit; you are just like your ancestors. Which of the prophets did your ancestors not persecute? They put to death those who foretold the coming of the righteous one, whose betrayers and murderers you have now become. You received the law as transmitted by angels, but you did not observe it.'
"When they heard this, they were infuriated, and they ground their teeth at him. But he, filled with the holy Spirit, looked up intently to heaven and saw the glory of God and Jesus standing at the right hand of God, and he said, 'Behold, I see the heavens opened and the Son of Man standing at the right hand of God.' But they cried out in a loud voice, covered their ears, and rushed upon him together. They threw him out of the city, and began to stone him. The witnesses laid down their cloaks at the feet of a young man named Saul. As they were stoning Stephen, he called out, 'Lord Jesus, receive my spirit.' Then he fell to his knees and cried out in a loud voice, 'Lord, do not hold this sin against them'; and when he said this, he fell asleep" (Acts 7:43-60).