The Lake County Sherrif's office has begun a criminal investigation into Schapp and the church after news of the affair leaked on Tuesday. Sherriff John Buncich did not give any specific details of the investigation.
According to CBS Chicago, the affair was discovered by a church deacon completely by accident.
"Jack Schaap had left his cell phone on the pulpit and a deacon had seen it on the pulpit and had picked it up to bring it back to him," Trisha Kee told CBS Chicago. "From what we understand, the deacon then saw a text come through from a teenage girl in the church, and it was a picture of Jack Schaap and this girl making out."
Kee, who moderates a Facebook page for ex-church members, also suggests that the unidentified girl received counseling from Schapp.
"She was also going to him for counseling," she added.
While the church would not confirm all of Kee's details, it admitted that her story was essentially correct. A spokeswoman told CBS Chicago that Schapp partook in "an improper relationship with a young woman and that they thought she was above the age of consent."
Eddie Wilson, the church's official spokesman, stated that Schaap was fired "due to a sin that has caused him to forfeit his right to be our pastor."
"Our church grieves over the need to take this action and the impact it will have on our people," Wilson continued. "We ask that everyone pray for the families involved and pray that the situation will be handled in a Christ-honoring manner. We look forward to the days ahead as we continue to service the needs of our surrounding community and the Chicago area."
Schaap has been the church's pastor for 11 years. In 2001, First Baptist Church of Hammond's former pastor passed away, and Schaap, who married his daughter, took up the pulpit. The couple are reportedly "trying to reconcile their marriage," according to Wilson.
To make things more inappropriate for Schaap, the former pastor has also produced a series of dating books aimed at teenagers. Among the titles of the series is "Is Teenage Love Real Love?" The answers to that question can easily be answered with "not if he's your pastor."