BELLO, Colombia — They were committed evangelicals, devoted to Jesus Christ.

But what some here called a spark, an inescapable pull of their ancestors, led them in a different direction, to Judaism. There were the grandparents who wouldn’t eat pork, the fragments of a Jewish tongue from medieval Spain that spiced up the language, and puzzling family rituals such as the lighting of candles on Friday nights.

So, after a spiritual journey that began a decade ago, dozens of families that had once belonged to a fire-and-brimstone church became Jews, converting with the help of rabbis from Miami and Jerusalem. Though unusual in one of the most Catholic of nations, the small community in Bello joined a worldwide movement in which the descendants of Jews forced from Spain more than 500 years ago are discovering and embracing their Jewish heritage....