The Detroit Free Press reported Edward Fride, the priest at Christ the King in Ann Arbor, suggested that church-goers take classes to carry a concealed pistol.
In a pro-gun letter to his congregation, he warned that crime had been rising in the area and budget cuts were reducing the number of armed police officers.
He highlighted mass killings at schools across the country, adding that police were supportive of "doing what is necessary to adequately protect our families and our homes."
The letter was titled 'We're not in Mayberry Anymore, Toto!', referencing a show set in North Carolina in the 1960s and Dorothy's dog from the Wizard of Oz.
The Detroit Press said he wrote: "It is very common for Christians to simply assume that they live in Mayberry, trusting that because they know the Lord Jesus, everything will always be fine and nothing bad can happen to them and their families.
"How to balance faith, reality, prudence, and trust is one of those critical questions that we struggle with all our lives.
"Pretending we are in Mayberry, while we are clearly not, can have very negative consequences for ourselves and those we love, especially those we have a responsibility to protect.
"If we are not in Mayberry, is there a real threat?"
It was reported that Mr Fride told parishioners that Catholic teachings do not stop Christians carrying a gun for self-defence and to defend others.
Michael Diebold, a spokesman for the Diocese of Lansing which oversees the Ann Arbor parish, confirmed Monday that the controversial letter had been sent.
He said: "Yes, it appears that 'We're Not in Mayberry Anymore, Toto!' was sent out to the parishioners of Christ the King by their pastor, Fr. Ed Fride."
Earl Boyea, t he Catholic Bishop of the Diocese of Lansing where Fr Fride serves, emphasised that guns and gun lessons do not belong in the church. Michael Diebold said the ban on weapons in church makes them "gun-free zones".
Mr Diebold referred to a 2012 statement by the Lansing bishop: "We are followers of Jesus Christ, who raised not a hand against those who mocked, tortured, and finally murdered him.
"While we grasp both the Second Amendment and the legitimate right of some persons to defend themselves, our churches and our schools are dedicated to a far different approach to life's problems."
Edward Fride said some parishioners told him they were afraid of carrying weapons: "Several people have said to me, I'm afraid of guns. My response to one woman was, 'Well, how do you feel about rape?''
