At about 11:30 p.m. Friday, Father Matthew Compton confronted the offender in the church, located in the 2800-block of West 81st Street in the Wrightwood neighborhood.
Compton, 41, noticed the offender as he exited an office and looked down the hall.
"I knew immediately it was not the pastor. That's why I immediately ran up to the individual and asked him, 'Who are you? What are you doing here?" the young Catholic priest said.
The young offender, who apparently entered via a dislodged air conditioner in the church office, had the clergyman's backpack and other personal items.
Compton told the man that they were in a house of God and that it was no place for a person with bad intentions.
"So he drops the backpack," the priest recounts, "and he says, 'I just want to get out of here.' And then I ask, who are you, and that's when he punched me in the side of the head."
On Monday, Compton showed off a few scratches on his right cheek. He said he is experiencing a bit of tenderness not unlike what one might feel from bumping one's head.
The punch led to a chase downstairs to a south-facing door.
"Again I confronted him, I said 'What are you doing here?' And his remark then was 'I am here to pray.' And then I said, 'No you're not," Compton said.
Church security video shows the young man eventually shoving his way out.
The church said a big screen TV, a laptop computer, a wallet and a backpack were taken.
Police continued to search for the man Monday evening.
This is not the first time the church, a fixture in the neighborhood for more than 70 years, was targeted. It was robbed two years ago and, since then, there were two more attempted robberies before Friday.
And in the spirit of its patron saint, who forgave his executioners at the moment of his death, Compton wanted to be clear he forgives his attacker.
"I would hope he realizes that he too is the son of God. God made him. God has made each of us. None of us are accidents. That God made him and he realizes that as a son of God, God wants good for him," Compton said.
Anyone with information is asked to contact Detective Mizera #20259 at 312-747-8730 or Area Central HQ at 312-747-8380.