Syncretism is one thing if it happens over centuries. Like let’s say you’re Italian. A long, long time ago your ancestors had a mid-winter festival in honor of Saturn celebrating the birth of the sun; and then Constantine, who ruled over those ancestors’ children, came along and converted to a new religion that was started by a guy called Jesus; and then those children’s children gradually came to believe that that Jesus was born at that same time, in the dead of winter, and. . .
But I keep thinking about those apostles who, just ten days ago, had seen Jesus’ body disappear; coming together there in Jerusalem to pray about the Torah; and then those tongues of fire appeared over their heads and they could suddenly speak all kinds of languages; and so they went out into Jerusalem and converted 3,000 people to this new religion.
Well I guess all that is pretty persuasive, and I guess it’s like suddenly becoming born-again. The only part I don’t get is why they were still celebrating Shavuot.