Complex sentence: It was also claimed that Spracklin's excessive zeal extended to his own parishioners, whose attention he would engage while preaching in the interior of Sandwich Methodist Church, while his associates, outside the building, would surreptitiously search his parishioners' cars at random.
Split into simpler sentences: It was also claimed that Spracklin's excessive zeal extended to his own parishioners. These their attention he would engage while preaching in the interior of Sandwich Methodist Church, while his associates, outside the building, would surreptitiously search his parishioners' cars at random.