ST. PAUL

Decades ago on a characteristically arctic day here, a boy named Scott Rosenberg waited with his neighborhood pals as a certain Chevy Impala glided into view. It contained the city’s archbishop, and the boys, all of them Roman Catholic except for Scott, pelted the car with snowballs.

The archbishop braked and emerged to chastise his assailants. To Scott, whom he correctly identified as Jewish, the prelate said simply, “You call your rabbi.”

Consider this a parable or a metaphor or just a piquant coincidence. Consider it revealing that Shmarya Rosenberg, as Scott is now known, recalled the incident in a recent interview as one of his most enduring memories. Because, lo, these years later, Mr. Rosenberg has made his name and earned equal measures of admiration and opprobrium for lobbing the digital version of snowballs at a great many rabbis.

Blogging on the site FailedMessiah.com, Mr. Rosenberg, 51, has transmuted a combination of muckraking reporting and personal grudge into a must-read digest of the actual and alleged misdeeds of the ultra-Orthodox world. He has broken news about sexual misconduct, smear campaigns and dubious business practices conducted by or on behalf of stringently religious Jews.