Complex sentence: After Cowdery baptized several new members, the Mormons received threats of mob violence; and before Smith could confirm the newly baptized members, he was arrested and brought to trial as a disorderly person.
Split into simpler sentences: After Cowdery baptized several new members, the Mormons began receiving threats of mob violence. Before Smith could confirm the newly baptized members, he was arrested and brought to trial as a disorderly person.